Ma kana muhammadun aba ahadin min rijalikum walakin rasoola Allahi wakhatama annabiyyeena (surah Ahzab: 40)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(33:40) Muhammad is not the father of any of your men, but he is the Messenger of Allah and the seal of the Prophets. Allah has full knowledge of everything. *77

Maa kaana Muhammmadun abaaa ahadim mir rijaalikum wa laakir Rasoolal laahi wa Khaataman Nabiyyeen; wa kaanal laahu bikulli shai`in `Aleema

*77) This one sentence arts at the root of aII those objections which the opponents were raising in connection with this marriage of the Holy Prophet. Their first objection was that he had married his own daughter-in-law, whereas according to his own law the son's wife is forbidden for the father. This was answered by saying: "Muhammad is not the father of any of your men." That is, Zaid was not his real son, and so it was not unlawful to marry his divorced wife. Their second objection was that even if his adopted son was not his real son, it was not necessary that he should have marred his divorced wife. This was answered by saying: '' . . . but he is the Messenger of AIlah." That is, it was his duty as the Messenger of Allah to put an end to all kinds of prejudices about a lawful thing which custom and tradition had made unlawful without good reason and declare it to be lawful once again.
The point was stressed by saying: " ... and (he is) the last of the Prophets." That is, not to speak of a Messenger, no other Prophet would be raised after him, who could make up for a possible deficiency in the enforcement of a reform in the law and society that might have been left un-enforced in his time. Therefore, it had become all the more necessary that he should himself root out the custom of ignorance.
Again, to further emphasize this point, it was said: "Allah has knowledge of everything. " that is, Allah knows best why it was imperative to get the custom of ignorance rooted out at that juncture through the Holy Prophet Muhammad (upon whom be Allah's peace) rather than let it remain as it was. He knows that no other prophet would be coming after him in the future; therefore, if He did not abolish this custom through His Last Prophet, no other person after him would be able to abolish it for alI the Muslims of the world for ever. Even if the later refomers would abolish it, no action of any one of them will havc the permanent and universal authority behind it so that the people of every country and every age might -start following it, and none of them would have a personality endowed with that holiness and sanctity that an action's being merely his way (Sunnah) might root out every feeling of aversion and abhorrence from the mind of the people.
It is a pity that a section of the people in our age have given wrong interpretations of this verse and opened the way to a great mischief. We have therefore added a comprehensive appendix at the end of the commentary of this Surah for the explanation of the question of the Finality of Prophethood and the eradication of the misunderstanding spread by these people.