That the Prophet said "If a Muhrim cannot find sandals then let him wear Khuffs, and cut them, so that they come lower than the ankles.'' (Using translation from Nasāʾī 2680)  

عَنِ النَّبِيِّ ﷺ قَالَ «إِذَا لَمْ يَجِدِ الْمُحْرِمُ النَّعْلَيْنِ فَلْيَلْبَسِ الْخُفَّيْنِ وَلْيَقْطَعْهُمَا أَسْفَلَ مِنَ الْكَعْبَيْنِ»