Which Surah did the Messenger of Allah, peace and blessings be upon him, say was the most eloquent Surah in the Qur’an?

There is no report from the Prophet, peace and blessings be upon him, indicating that a specific surah (definition) of the Quran is more eloquent than others. While there may be verses that combine aspects of eloquence not found in others, the eloquence, greatness, and sublimity of the Quran’s meanings do not vary to the extent that one part could be said to be more eloquent than another.

Al-Zarkashi clarified that the meaning of saying "this speech is more eloquent than that" is that each context has its own beauty and subtlety. Thus, the eloquence of a surah like "May the hands of Abu Lahab be ruined" in its supplication for loss is no less than the eloquence of "Say, 'He is Allah, [who is] One'" in its monotheistic message. It is not appropriate to compare them on the basis of a difference in absolute eloquence; rather, every verse is as eloquent as possible within its specific context and the situation in which it was revealed.