Sūrah No. 77, Revealed in Makkah, 50 verses.
The Sūrah gets its name from the emissaries mentioned in the first verse.
The verse Woe to the deniers on that day! is repeated ten times in this Sūrah, each time after a new detail about the Day of Judgment. Tafsīr Namūne says this repetition is reminiscent of Sūrat al-Rahmān except that Sūrat al-Rahmān talks about blessings while this Sūrah talks about the punishment awaiting the rejecters of faith.
It is reported that once the Prophet a was told ‘you have aged quickly, O Messenger of God’ and he replied ‘Sūrahs Hūd, al-Wāqi‘ah, al-Mursalāt, and ‘Ammā Yatasā’alūn(Naba’) have aged me.’ Note that all these four Sūrahs talk about the Day of Judgment and the frightening events of that day.