The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 1185
Abu Huraira reported: The Messenger of Allah (may peace be upon him) said two rak'ahs of the noon prayer and then gave salutation when a man from Band Sulaim came to him and said: Messenger of Allah. has the prayer been shortened, or have you forgotten? -and the rest of the hadith is the same.