Sahih Muslim Book 4, Hadith Number 1688.

Chapter : Encouragement to observe prayers during Ramadhan and that is Tarawih.

Jabir b. ‘Abdullah reported: I accompanied the Messenger of Allah (may peace be upon him) in a journey and we reached a watering place. He said: Jabir, are you going to enter it? I said: Yes. The Messenger of Allah (may peace be upon him) then got down and I entered it. He (the Holy Prophet) then went away to relieve himself and I placed for him water for ablution. He then came back and performed ablution, and then stood and prayed in one garment, having its ends tied from the opposite sides. I stood behind him and he caught hold of my ear and made me stand on his right side.