The Book of Mosques and Places of Prayer-03a

The reciter: Abu al-Tahir and Harimah narrated to us, saying: Ibn Wahb narrated to us from Yunus. He said: And Zuhayr ibn Harb narrated to us, saying: Ya'qub ibn Ibrahim narrated to us, saying: My father narrated to us, both of them from Ibn Shihab, from Humayd ibn 'Abd al-Rahman, that Abu Hurayrah and Abu Sa'id informed him: similar to the hadith of Ibn 'Uyaynah.

The Shaykh : This contains guidance to spit to one's left or under one's left foot, and here it is possible that it is a doubt from the narrator, and it is possible that it is for variation. If the matter turns between it being for variation or it being a doubt from the narrator, the preferred course is to take it as variation, because the default is the absence of doubt, and combining is possible, meaning it is possible to say: either it is to his left or under his left foot. He said "under his left foot" because the left is more deserving of harm than the right. If someone asks: if he is in the mosque, how can he spit to his left or under his left foot? We say: if he is the last person in the row on the left and the mosque wall is short, he can spit to his left. As for anything other than that, or under his left foot, that is not possible, but he spits in his garment and rubs part of it with another part to remove its appearance, because souls dislike seeing such a thing.