Sahih Bukhari
Prayers (Salat)
Volume: 001 / Book Number: 008 / Hadith Number: 419
Narrated 'Aisha:
Um Habiba and Um Salama mentioned about a church they had seen in Ethiopia in which there were pictures. They told the Prophet about it, on which he said, "If any religious man dies amongst those people they would build a place of worship at his grave and make these pictures in it. They will be the worst creature in the sight of Allah on the Day of Resurrection."