(1) باب مَا يُبَاحُ لِلْمُحْرِمِ بِحَجٍّ أَوْ عُمْرَةٍ وَمَا لاَ يُبَاحُ وَبَيَانِ تَحْرِيمِ الطِّيبِ عَلَيْهِ
Jabir (Allah be pleased with him) reported Allah's Messenger (ﷺ) as saying:
He who does not find shoes to wear may wear socks, and he who does not find lower garment to wear may put on trousers.
Reference: Sahih Muslim 1179
In-book reference: Book 15, Hadith 7
USC-MSA web (English) reference(deprecated numbering scheme): Book 7, Hadith 2653