Musnad Ahmad 27:978

'Affan narrated to us, 'Abd al-'Aziz ibn Muslim narrated to us, from 'Abdullah ibn Dinar, from 'Abdullah ibn 'Umar, that the Messenger of Allah (may Allah bless him and grant him peace) forbade the *muhrim* (one in the state of ihram) from wearing a garment dyed with *wars* (a yellow plant) or saffron. And he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever does not have sandals, let him wear leather socks (*khuffayn*), and let him cut them below the ankles."