Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Umm Saeed. She says: I brought sahur (pre-dawn meal) to Hazrat Ali (may Allah be pleased with him) and placed it before him. And he was performing prayer at that time. Then when he finished the prayer, he said: Why did you not cover it? Did you see when Satan put his mouth in it? Throw it away. He refused to drink it.