It is narrated from Sayyiduna Safinah (may Allah be pleased with him) that Sayyiduna Ali (may Allah be pleased with him) invited a man and prepared food for him. Sayyidah Fatimah (may Allah be pleased with her) said: If we invite the Prophet (peace and blessings be upon him) too, he (peace and blessings be upon him) could eat with us. So they sent a man to him (peace and blessings be upon him). He (peace and blessings be upon him) came and took hold of the two doorposts, and saw a (decorated) curtain on the two sides of the house, so he turned back. Sayyidah Fatimah (may Allah be pleased with her) said to Sayyiduna Ali (may Allah be pleased with him): Follow him and see why he turned back. So he followed him (peace and blessings be upon him) and said: O Messenger of Allah, what made you turn back? He (peace and blessings be upon him) said: "It is not fitting for me to enter a decorated house."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6416