Mishkat al-Masabih #716

Abu Huraira reported God’s Messenger as saying, “When any of you prays he should not place his sandals at his right or at his left so as to be at the right of someone else, unless no one is at his left, but should place them between his feet.” A version has, “or pray with them on.” Abu Dawud transmitted it and Ibn Majah transmitted something to the same effect.