Argument
The hadith literature portray Muhammad as someone who abuses innocent people, as could be seen in the following ahaadith:
A'isha reported that two persons visited Allah's Messenger (ﷺ) and both of them talked about a thing, of which I am not aware, but that annoyed him and he invoked curse upon both of them and hurled malediction, and when they went out I said: Allah's Messenger, the good would reach everyone but it would not reach these two. He said: Why so? I said: Because you have invoked curse and hurled malediction upon both of them. He said: Don't you know that I have made condition with my Lord saying thus: O Allah, I am a human being and that for a Muslim upon whom I invoke curse or hurl malediction make it a source of purity and reward. [Saheeh Muslim, Book 32, Hadith 6285]
Salim, the freed slave of Nasriyyin, said: I heard Abu Huraira as saying that he heard Allah's Messenger (ﷺ) as saying: O Allah, Muhammad is a human being. I lose my temper just as human beings lose temper, and I have held a covenant with Thee which Thou wouldst not break: For a believer whom I give any trouble or invoke curse or beat, make that an expiation (of his sins and a source of) his nearness to Thee on the Day of Resurrection. [Saheeh Muslim, Book 32, Hadith 6293]
Anas b. Malik reported that there was an orphan girl with Umm Sulaim (who was the mother of Anas). Allah's Messenger (ﷺ) saw that orphan girl and said: O, it is you; you have grown young. May you not advance in years! That slave-girl returned to Umm Sulaim weeping. Umm Sulaim said: O daughter, what is the matter with you? She said: Allah's Apostle (ﷺ) has invoked curse upon me that I should not grow in age and thus I would never grow in age, or she said, in my (length) of life. Umm Sulaim went out wrapping her head-dress hurriedly until she met Allah's Messenger (ﷺ). He said to her: Umm Sulaim, what is the matter with you? She said: Allah's Apostle, you invoked curse upon my orphan girl. He said: Umm Sulaim, what is that? She said: She (the orphan girl) states you have cursed her saying that she might not grow in age or grow in life. Allah's Messenger (ﷺ) smiled and then said: Umm Sulaim, don't you know that I have made this term with my Lord. And the term with my Lord is that I said to Him: 1 am a human being and I am pleased just as a human being is pleased and I lose temper just as a human being loses temper, so for any person from amongst my Ummah whom I curse and he in no way deserves it, let that, O Lord, be made a source of purification and purity and nearness to (Allah) on the Day of Resurrection. [Saheeh Muslim, Book 32, Hadith 6297]
Response
The Prophet (peace be upon him) was not known to be an abuser:
Narrated Anas: Allah's Messenger (ﷺ) was neither a Fahish (one who had a bad tongue) nor a Sabbaba (one who abuses others)... [Saheeh Bukhari, Vol. 8, Book 73, Hadith 72]
So how do we then make sense of this in light of the aforementioned ahaadith?
When it comes to the first hadith mentioned above, the Prophet (peace be upon him) could have sincerely made Ijtihad and concluded that those two men were worthy of being cursed, for the Prophet (peace be upon him) could only judge by that which is apparent and does not know that which is hidden.[1] What confirms the fact that the Prophet (peace be upon him) judges by the apparent and could be mistaken in doing so is the following tradition:
Umm Salamah (May Allah be pleased with her) reported: Messenger of Allah (ﷺ) said, "Verily, I am only a human and the claimants bring to me (their disputes); perhaps some of them are more eloquent than others. I judge according to what I hear from them). So, he whom I, by my judgment, (give the undue share) out of the right of a Muslim, I in fact give him a portion of (Hell) Fire". [Reported in Bukhari and Muslim]
He emphasized that he does not judge by the internal beliefs of people:
The Messenger of Allah (ﷺ) said: I have not been commanded to pierce through the hearts of people, nor to split their bellies (insides). [Saheeh Bukhari, Book 5, Hadith 2319]
As for the Prophet's (peace be upon him) statement, "Don't you know that I have made condition with my Lord saying thus: O Allah, I am a human being and that for a Muslim upon whom I invoke curse or hurl malediction make it a source of purity and reward.", this is in reference to those whom he has wrongly cursed. This is due to the possibility that the outward state of the cursed person did not reflect his inward state, which is what the Prophet (peace be upon him) is judging upon.
Now we move on to the second and third ahaadith and the Prophet's (peace be upon him) remark that he loses his temper just as any human being loses his temper. This is to be understood as "anger for the sake of Allah" in the Prophet's (peace be upon him) regard. It may be that the Prophet (peace be upon him) favored cursing the individual over punishing him for sinning. The Prophet (peace be upon him) is also pointing out to his Ummah that anger may at times result in crossing the bounds of Allah.[2]
As mentioned earlier, the Prophet (peace be upon him) can be mistaken in his judgment, and as a result of his mistake, Allah would transform his curse into a blessing upon the person. So at the end of the day, the Prophet (peace be upon him) is really hurting nobody unjustly.
It has also been suggested that what the Prophet (peace be upon him) was truly worried about mistakenly saying something which appeared to be a curse, but actually was not intended to be so, actually befalling upon someone. During that time, it was the habit of Arabs to say things that appeared to be a curse (but were not) to drive a certain point.
For example, we read in Sunan an-Nasa'i, Vol. 4, Book 26, Hadith 3232:
Narrated Abu Hurairah: It was narrated from Abu Hurairah that the Prophet said: "Women are married for four things: their wealth, their nobility, their beauty and their religious commitment. Choose the one who is religiously committed, may your hands be rubbed with dust."
"Hands being rubbed with dust" entails one is so poor that he has nothing in his hands except for dust. In no way does anyone understand that the Prophet (peace be upon him) is praying for anyone to be poor; rather, it is a phrase Arabs were used to saying, while not intending it to be a prayer.[3]
The phrase, "may your hands be rubbed with dust," was used by the Prophet (peace be upon him) in different contexts, and the intent was not to be a negative prayer upon the person.[4]
Let us look at another example from Saheeh Muslim, Book 7, Hadith 2783:
A'isha (Allah be pleased with her) reported: We went with the Messenger of Allah (ﷺ) and we did not see but that he (intended to perform) Hajj (only), but when we reached Mecca we circumambulated the House; and the Messenger of Allah (ﷺ) commanded that he who did not have with him a sacrificial animal should put off Ihram. She (A'isha) said: (And consequently) those who did not bring the sacrificial animals with them put off Ihram; and among his wives (too) who had not brought the sacrificial animals with them put off Ihram. A'isha said: I entered my period and could not (therefore) circumambulate the House. When it was the night of Hasba she said: Messenger of Allah, people are coming back (after having performed both) Hajj and'Umra, whereas I am coming back only with Hajj, whereupon he said: Did you not circumambulate (the Ka'ba) that very night we entered Mecca? She (A'isha) said: No, whereupon he said: Go along with your brother to Tan'im and put on the Ihram for Umra, and it is at such and such a place that you can meet (us). (In the meanwhile) Safiyya (the wife of the Holy Prophet) said: I think, I will detain you (since I have entered in the monthly) period and you shall have to wait for me for the farewell circuit). Thereupon he (the Holy Prophet) said: May you be wounded and your head shorn did you not circumambulate on the Day of Sacrifice (10th of Dhu'l-Hijja)? She said: Yes. The Prophet (ﷺ) said: There is no harm. You should go forward. 'A'isha said: The Messenger of Allah (ﷺ) was going upwards to the side of Mecca, whereas I was coming down from it, or I was going upward, whereas he was coming down. Isbiq said: She was climbing down, and he was climbing down.
Once again, we see the Prophet (peace be upon him) said something which appears to be a curse of some sort, "May you be wounded and your head shorn." However, if we take it literally, we are left scratching our heads wondering why the Prophet (peace be upon him) would curse his wife when the entire context of the story shows that she did absolutely nothing wrong! Clearly, this was not literal, as this phrase over time with the Arabs was not being used in a literal fashion anymore.[5]
So in light of this, we can see that it is plausible that the Prophet (peace be upon him) was wary of this and worried that these might become prayers that get answered despite them not being intentional. As a result, the Prophet (peace be upon him) prayed that they are turned into blessings.
In conclusion, we see that the Prophet (peace be upon him) used to judge people by that which is apparent when they commit sins, and he would do so feeling angry for the sake of Allah for believing that the individual committed wrong. However, it is possible that the Prophet (peace be upon him) judged a person whose outward actions did not reflect his inward state. The Prophet (peace be upon him) was aware of this and out of precaution, asked Allah to turn any unjustified curses into blessings for those people.
It was also a habit of the Arabs to say phrases that appeared to be curses, but were not intended to be so literally. The Prophet (peace be upon him) may have possibly been worried that these could turn into answered prayers. So once again, out of precaution, the Prophet (peace be upon him) asked Allah to turn any such uttered phrases into blessings for those people.
Thus, in reality, what we see here is actually the Prophet's God-fearing, merciful and just nature (peace be upon him), rather than an abusive person who just invoked curses upon innocent people.
[1] Imam an-Nawawi stated in his commentary on Saheeh Muslim:
أحدهما أن المراد ليس بأهل لذلك عند الله تعالى، وفي باطن الأمر، ولكنه في الظاهر مستوجب له، فيظهر له صلى الله عليه وسلم استحقاقه لذلك بأمارة شرعية، ويكون في باطن الأمر ليس أهلا لذلك، وهو صلى الله عليه وسلم مأمور بالحكم بالظاهر، والله يتولى السرائر.
Ibn Hajar al-Asqalani, in his Fathul Baari, quotes al-Maaziri as saying:
ان قيل كيف يدعو صلى الله عليه و سلم بدعوة على من ليس لها بأهل قيل ا لمراد بقوله ليس لها بأهل عندك في باطن امره لا على ما يظهر مما يقتضيه حاله وجنايته حين دعائي عليه فكأنه يقول من كان باطن امره عندك انه ممن ترضى عنه فاجعل دعوتي عليه التي اقتضاها ما ظهر لي من مقتضى حاله حينئذ طهورا وزكاة قال وهذا معنى صحيح لا احالة فيه لأنه صلى الله عليه و سلم كان متعبدا بالظواهر وحساب الناس في البواطن على الله انتهى وهذا مبني على قول من قال انه كان يجتهد في الاحكام ويحكم بما أدى إليه اجتهاده واما من قال كان لا يحكم الا بالوحي فلا يتأتى منه هذا الجواب
[2] Ibn Hajar al-Asqalani said in his Fathul Baari, quoting al-Maaziri:
فإن قيل فما معنى قوله وأغضب كما يغضب البشر فإن هذا يشير إلى أن تلك الدعوة وقعت بحكم سورة الغضب لا أنها على مقتضى الشرع فيعود السؤال فالجواب أنه يحتمل أنه أراد أن دعوته عليه أو سبه أو جلده كان مما خير بين فعله له عقوبة للجاني أو تركه والزجر له بما سوى ذلك فيكون الغضب لله - تعالى - بعثه على لعنه أو جلده ولا يكون ذلك خارجا عن شرعه . قال ويحتمل أن يكون ذلك خرج مخرج الإشفاق وتعليم أمته الخوف من تعدي حدود الله فكأنه أظهر الإشفاق من أن يكون الغضب يحمله على زيادة في عقوبة الجاني لولا الغضب ما وقعت أو إشفاقا من أن يكون الغضب يحمله على زيادة يسيرة في عقوبة الجاني لولا الغضب ما زادت ويكون من الصغائر على قول من يجوزها أو يكون الزجر يحصل بدونها
[3] Linguist expert Ibn Mandhur said in his Lisaan al-'Arab:
ويرون والله أعلم أن النبي صلى الله عليه وسلم لم يتعمد الدعاء عليه بالفقر ولكنها كلمة جارية على ألسن العرب يقولونها وهم لا يريدون بها الدعاء على المخاطب ولا وقوع الأمر بها .
He even goes on to list examples of how the Arabs could use phrases, which outwardly appear to be rebukes and insults, yet are actually compliments:
وكثيرا ترد للعرب ألفاظ ظاهرها الذم وإنما يريدون بها المدح كقولهم لا أب لك ولا أم لك وهوت أمه ولا أرض لك ونحو ذلك
[4] See an-Nawawi's, Sharh Muslim; Ibn Battal's, Sharh al-Bukhari; as-Suyuti's, Tanweer al-Hawaalik Sharh Muwatta' Malik; Badr ad-Deen's, 'Umdat al-Qari fi Sharh Saheeh al-Bukhari; as-Sindi's, Haashiya 'ala al-Nasai' & at-Tibrizi's, Sharh Mishkaat al-Masaabeeh.
[5] Imam an-Nawawi said in his commentary on Saheeh Muslim:
اتسعت العرب فيها فصارت تطلقها ولا تريد حقيقة ما وضعت له