It was narrated that 'Ubaid bin Juraih said:
"I said to Ibn 'Umar: 'I see you are wearing Sibtiyyah sandals, [1] and you performed Wudu' in them.' He said: 'I saw the Messenger of Allah (ﷺ) wearing then and performing Wudu' in them.'"[1] Made of hairless, tanned leather.
Arabic/English book reference: Vol. 1, Book 1, Hadith 117