The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 907
Ma'n reported.. I heard it from my father who said: I asked Masruq who informed the Messenger of Allah (may peace be upon him) about the night when they heard the Qur'an. He said: Your father, Ibn Mas'ud, narrated it to me that a tree informed him about that.