Sunan Ibn Majah Book 25, Hadith 50

“I heard the Prophet (ﷺ) delivering a sermon – (one of the narrators) Hisham said: ‘On the pulpit’ – and he said: ‘Whoever does not have a waist wrap, let him wear pants or pajamas, and whoever does not have sandals, let him wear leather socks.’” In his narration, Hisham said: “If he does not find any, then let him wear pants or pajamas.”