Musannaf Ibn Abi Shaybah 8105 — Those who permitted praying in sandals

Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) says: The Prophet (peace and blessings be upon him) took off his sandals in prayer, so the people also took off their sandals. When he had completed the prayer, he asked the people: "Why did you take off your sandals?" They said: "We saw you take off your sandals, so we took off ours as well." He said: "Jibril came to me and told me that there was filth on my sandals. When any of you comes to pray, let him turn his sandals over and look at them; if there is filth on them, let him wipe it off against the ground and pray in them."