Tafsir of Hud 11:74

{فَلَمَّا ذَهَبَ عَنْ إِبْرَاهِيمَ الرَّوْعُ} The fear he felt when he did not recognize his guests. The meaning is: when his heart was reassured after the fear, and he was filled with joy due to the good tidings that replaced his distress, he became free to argue.

If you ask: Where is the answer to lamma (when)? I say: It is omitted, just as it was omitted in His saying: {So when they took him and agreed...} (Yusuf: 15). The phrase {he began to argue with Us} is a new sentence that indicates the answer. Its estimation is: "He became bold enough to address Us," or "He turned his attention to arguing with Us," or "He said such and such." Then He began by saying: {he began to argue with Us concerning the people of Lot}.

It is said regarding {he began to argue with Us}: It is the answer to lamma, and it was brought in the present tense (mudari') to depict the state of the event. It is also said that lamma turns the present tense into the meaning of the past, just as in turns the past into the meaning of the future. It is also said: Its meaning is "he began to argue with Us" or "he proceeded to argue with Us."

The meaning is: He argued with Our messengers. His argument with them was that they said: {We are going to destroy the people of this town} (Al-Ankabut: 31). He said: "Do you see, if there were fifty believers in it, would you destroy it?" They said: "No." He said: "Forty?" They said: "No." He said: "Thirty?" They said: "No," until he reached ten. They said: "No." He said: "Do you see, if there were one Muslim man in it, would you destroy it?" They said: "No." At that point, he said: {Indeed, Lot is in it} (Al-Ankabut: 32). They replied: {We know best who is in it; we will surely save him and his family} (Al-Ankabut: 32).

{Concerning the people of Lot} means regarding their situation. From Ibn Abbas: They said to him, "If there are five in it who pray, the punishment will be lifted from them." From Qatadah: "What a people who do not have ten among them who possess goodness." It is said there were four million people in it.

{Indeed, Abraham was forbearing}—not hasty toward those who wronged him. {Compassionate}—frequently sighing out of fear of sins. {Returning}—repentant, turning back to Allah with what He loves and is pleased with.

These attributes indicate tenderness of heart, compassion, and mercy. Thus, it is explained that this is what moved him to argue on their behalf, hoping that the punishment would be lifted from them and that they would be granted respite, perhaps they might repent and turn back, just as it moved him to seek forgiveness for his father.