Musannaf Ibn Abi Shayba 3:5077

Waki’ narrated to us, he said: Al-A’mash narrated to us, from Abu Wa’il, from Hudhayfah, who said: The Muslim servant, when he performs ablution and perfects the ablution, then stands to pray, Allah turns His Face toward him until he is the one who turns away or commits an evil act. So he should not spit in front of him, nor to his right, for to his right is the recorder of good deeds. Rather, he should spit to his left or behind his back.