Musnad Ahmad 3:67

'Affan narrated to us, 'Abd al-Warith narrated to us, Ayyub ibn Musa narrated to us, Nabih ibn Wahb narrated to me: That the eye of 'Umar ibn 'Ubayd Allah ibn Ma'mar became inflamed while he was in the state of ihram, so he wanted to apply kohl to it. Aban ibn 'Uthman forbade him and ordered him to dress it with aloe (sabir). And he claimed that 'Uthman narrated from the Messenger of Allah, may Allah bless him and grant him peace, that he did that.