Sahih Bukhari Volume 1, Book 12, Hadith Number 784

Narated By Thabit : Anas said, “I will leave no stone unturned in making you offer the prayer as I have seen the Prophet making us offer it.” Anas used to do a thing which I have not seen you doing. He used to stand after the bowing for such a long time that one would think that he had forgotten (the prostrations) and he used to sit in-between the prostrations so long that one would think that he had forgotten the second prostration.