I heard Messenger of Allah ﷺ say as he was delivering an address: So far as the trousers are concerned, one who does not find lower garment, he may wear them; as also socks, he may wear them who does not find shoes. It concerns the Muhrim. (Using translation from Muslim 1178a)
سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ «السَّرَاوِيلُ لِمَنْ لَمْ يَجِدِ الْإِزَارَ وَالْخِفَافُ لِمَنْ لَمْ يَجِدِ النَّعْلَيْنِ» يَعْنِي الْمُحْرِمَ