Sahih Bukhari Volume 005, Book 058, Hadith Number 154.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 58. Merits of the Helpers in Madina (Ansaar)
Narated By Anas bin Malik : The Prophet said to Ubai, "Allah has ordered me to recite to you: 'Those who disbelieve (Surat-al-Bayina 98).' " Ubai said, "Has He mentioned my name?" The Prophet said, "Yes." On hearing this, Ubai started weeping.