I heard the Prophet ﷺ giving a sermon in which he said, "Trousers may be worn by anyone in ihram who cannot find a waist-wrapper, and leather socks by anyone who cannot find sandals."
أخبرنا قتيبة قال حدثنا حماد عن عمرو عن جابر بن زيد
سمعت النبي ﷺ يخطب وهو يقول السراويل لمن لا يجد الإزار والخفين لمن لا يجد النعلين للمحرم
Muslim narrated it in the Hajj chapter, section on what is permitted for one in the state of ihram for Hajj or umrah to wear and what is not permitted, hadith no. 1178, from Qutayba, and Bukhari narrated it in the chapter on the recompense for hunting, section on wearing khuffs for one in the state of ihram if he cannot find sandals, hadith no. 1841, from the hadith of Amr bin Dinar as narrated here. It is also found in Al-Kubra, hadith no. 3651.Hammad is Ibn Zayd.