Hadith 13:75
Al-Hasan said on Samura’s authority that God’s Messenger forbade that a thong of a sandal should be cut off between two toes. Abu Dawud transmitted it.
وَعَن الحسنِ عَنْ سَمُرَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ نَهَى أَنْ يُقَدَّ السَّيْرُ بَيْنَ أُصبعَينِ. رَوَاهُ أَبُو دَاوُد
Original Reference: Mishkat al-Masabih 3528