Sunan Ibn Majah, Volume 4, Book 32, Hadith 3614 (DarusSalam) ⓘ
It was narrated that ‘Abdullah bin ‘Abbas said: “The sandals of the Prophet had two thongs doubled around their straps.”
حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا وَكِيعٌ، عَنْ سُفْيَانَ، عَنْ خَالِدٍ الْحَذَّاءِ، عَنْ عَبْدِ اللَّهِ بْنِ الْحَارِثِ، عَنْ عَبْدِ اللَّهِ بْنِ الْعَبَّاسِ، قَالَ كَانَ لِنَعْلِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قِبَالاَنِ مَثْنِيٌّ شِرَاكُهُمَا .
also referenced under: Hadith 3614 (Reference) & Book 32, Hadith 3745 (In-Book)