Ash-Shama'il Al-Muhammadiyah, Book 11, Hadith 86 (In-Book)

Abu Hurayrah radiallahu anhu says that the shoes of Sayyidina Rasulullah sallallahu alaihe wasallam had two straps. In the same manner the shoes of Abu Bakr and Umar radiallahu anhu had two straps on them. Sayyidina 'Uthman radiallahu anhu began the use of one strap.

حَدَّثَنَا مُحَمَّدُ بْنُ مَرْزُوقٍ أَبُو عَبْدِ اللهِ، قَالَ‏:‏ حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ قَيْسٍ أَبُو مُعَاوِيَةَ، قَالَ‏:‏ حَدَّثَنَا هِشَامٌ، عَنْ مُحَمَّدٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ‏:‏ كَانَ لِنَعْلِ رَسُولِ اللهِ صلى الله عليه وسلم قِبَالانِ وَأَبِي بَكْرٍ وَعُمَرَ، وَأَوَّلُ مَنْ عَقَدَ عَقْدًا وَاحِدًا عُثْمَانُ رضي الله عنه‏.‏‏.‏

also referenced under: Book 10, Hadith 81 (English)