Yahya related to me from Malik from Humayd ibn Qays from Ata ibn
Rabah that a bedouin came to the Messenger of Allah, may Allah bless
him and grant him peace, when he was at Hunayn, and he was wearing a
shirt with traces of yellow on it. He said, "Messenger of Allah, I
have entered ihram for umra. What should I do?" The Messenger of
Allah, may Allah bless him and grant him peace, said to him, "Take off
your shirt and wash off this yellowness and do in umra as you would do
on hajj."
Muwatta Malik Book 20, Hadith 20