Sahih al-Bukhari, Volume 7, Book 72, Hadith 695 (USC-MSA) ⓘ
Narrated Ibn `Abbas: The Prophet said, "Whoever cannot get an Izar, can wear trousers, and whoever cannot wear sandals can wear Khuffs (socks made from thick fabric or leather)."
حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا سُفْيَانُ، عَنْ عَمْرٍو، عَنْ جَابِرِ بْنِ زَيْدٍ، عَنِ ابْنِ عَبَّاسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " مَنْ لَمْ يَجِدْ إِزَارًا فَلْيَلْبَسْ سَرَاوِيلَ، وَمَنْ لَمْ يَجِدْ نَعْلَيْنِ فَلْيَلْبَسْ خُفَّيْنِ " .
also referenced under: Book 77, Hadith 22 (In-Book) & Hadith 5804 (DarusSalam)