Sahih Muslim Book 004, Hadith Number 1692.
Chapter : Encouragement to observe prayers during Ramadhan and that is Tarawih.
This Hadith has been narrated on the authority of Ibn 'Abbas through another chain of transmitters and with slight alteration of two words. Instead of the word Qayyam (Supporter, as used in the above Hadith here the word) Qayyim (the Custodian) has been used, and he (further said): "What I did in secret." And in the Hadith narrated by Ibn 'Uyaina there is some addition.