Musnad Ahmad 1153:243

Yahya narrated to us, from Hisham, who said: My father, and Waki’ narrated to us, Hisham narrated to us—the meaning is the same—he said: My father narrated to me, from Aisha, that Umm Habibah and Umm Salamah mentioned a church they had seen in Abyssinia, in which there were images. The Messenger of Allah (peace and blessings of Allah be upon him) said: "Those people, when a righteous man among them would die, they would build a place of worship over his grave and depict those images in it. Those are the worst of creation in the sight of Allah the Almighty on the Day of Resurrection." Ahmad said: Waki’ said: They were discussing it in the presence of the Prophet (peace and blessings of Allah be upon him) during his illness, and Umm Salamah and Umm Habibah mentioned a church they had seen in the land of Abyssinia.