Mishkat al-Masabih

Anas said the Prophet’s sandal had two thongs. Bukhari transmitted it.

وَعَنْ أَنَسٍ قَالَ: إِنَّ نَعْلَ النَّبِيِّ صَلَّى الله عَلَيْهِ وَسلم كَانَ لَهَا قبالان