Musnad Ahmad 949:4

Abu Kamil narrated to us, Hammad—meaning Ibn Salamah—narrated to us, from Sa’id ibn Jumhan, who said: I heard Safinah narrating that a man was a guest of Ali ibn Abi Talib, so they prepared food for him. Fatimah said: "If only we had invited the Messenger of Allah (peace and blessings of Allah be upon him) so he could eat with us." So they sent for him, and he came and took hold of the two doorposts. There was a curtain (qiram) that had been hung in a corner of the house. When the Messenger of Allah (peace and blessings of Allah be upon him) saw it, he turned back. Fatimah said to Ali: "Follow him and ask him: 'What made you turn back?'" So he followed him and said: "What made you turn back, O Messenger of Allah?" He said: "It is not for me, or it is not for a prophet, to enter a decorated house."