I heard the Prophet ﷺ delivering a sermon at ʿArafat saying, "If a Muhrim does not find slippers, he could wear Khuffs (socks made from thick fabric or leather, but he has to cut short the Khuffs below the ankles), and if he does not find an Izar (a waist sheet for wrapping the lower half of the body) he could wear trousers." (Using translation from Bukhārī 1841)
سَمِعْتُ النَّبِيَّ ﷺ يَخْطُبُ بِعَرَفَاتٍ وَهُوَ يَقُولُ «مَنْ لَمْ يَجِدِ النَّعْلَيْنِ فَلْيَلْبَسِ الْخُفَّيْنِ وَمَنْ لَمْ يَجِدْ إِزَارًا فَلْيَلْبَسْ سَرَاوِيلَ»