Musannaf Ibn Abi Shayba 3:1085

Abu Ali al-Hasan ibn Sa'd narrated to us, he said: Baqi ibn Makhlad narrated to us, he said: Abu Bakr narrated to us, he said: Waki' narrated to us, he said: Hushaym narrated to us, from his father: Umar missed a man in the morning prayer, so he sent for him, and he came. He said: "Where were you?" He said: "I was sick, and had your messenger not come to me, I would not have gone out." Umar said: "If you are going out to anyone, then go out for the prayer."