"I asked Anas bin Malik: 'How were the sandals of the Messenger of Allah ﷺ ? He said: 'They had two straps.'"  

قُلْتُ لأَنَسِ بْنِ مَالِكٍ كَيْفَ كَانَ نَعْلُ رَسُولِ اللَّهِ ﷺ قَالَ لَهُمَا قِبَالاَنِ  

From Anas: "The sandals of the Prophet ﷺ had two straps."  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ نَعْلاَهُ لَهُمَا قِبَالاَنِ