Abu Dawud Book 21, Hadith Number 3746.
Chapter : Not known.
Narated By Ali ibn AbuTalib : Safinah AbuAbdurRahman said that a man prepared food for Ali ibn AbuTalib who was his guest, and Fatimah said: I wish we had invited the Apostle of Allah (PBUH) and he had eaten with us. They invited him, and when he came he put his hands on the side-ports of the door, but when he saw the figured curtain which had been put at the end of the house, he went away. So Fatimah said to Ali: Follow him and see what turned him back. I (Ali) followed him and asked: What turned you back, Apostle of Allah? He replied: It is not fitting for me or for any Prophet to enter a house which is decorated.