Sahih Muslim Book 4, Hadith Number 1031.

Chapter : The excellence of the prayer and the way it is begun and the excellence of Ruku’ and moderation in it and prostration and moderation in it, etc.

Yazid reported: Salama sought to say prayer near the pillar which was by that place where copies of the Qur’an were kept. I said to him: Abu Muslim. I see you striving to offer your prayer by this pillar. He said: I saw the Messenger of Allah (may peace be upon him) seeking to pray by its side.