1؎: The Prophet (sallallahu alayhi wa sallam) used to wear sandals, and by "straps" it is meant that each shoe had two leather loops at the front; in one loop he would insert the big toe and the second toe, and in the other loop the remaining toes.
Explanation & Benefits
Maulana Ataullah Sajid
Benefits and Issues:
➊ The construction of shoes in the time of the Prophet (sallallahu alayhi wa sallam) resembled the modern-day flip-flop. There was a piece of leather (shis‘) that would be placed between the toes. One end of it would be tied to the strap (zimaam). The strap is also called qibaal.
➋ In this type of shoe, most of the foot remains exposed; therefore, the Messenger of Allah (sallallahu alayhi wa sallam), when wiping over leather socks (khuffayn) or socks (jawrabayn), would not remove his feet from the shoes, but would wipe over them along with the shoes. See: (Sunan Ibn Majah, Hadith: 560, 559) In fact, without removing the shoes, he would even wash his feet. (Sahih al-Bukhari, Book of Ablution, Chapter: Washing the feet in the sandals and not wiping over the sandals, Hadith: 166)
Source: Commentary on Sunan Ibn Mājah by Mawlānā ‘Atā’ullāh Sājid, Page: 3614