Sahih Bukhari Volume 2, Book 19, Hadith Number 184.

Narated By Abu Rafi : I offered the ‘Isha’ prayer behind Abu Huraira and he recited Idhas-Sama’ Un-Shaqqat, and prostrated. I said, “What is this?” Abu Huraira said, “I prostrated behind Abu-l-Qasim and I will do the same till I meet him.”