Muwatta Imam Malik Book of Hajj, Hadith 18

Yahya related to me from Malik from Humayd ibn Qays from Ata ibn Rabah that a bedouin came to the Messenger of Allah ﷺ 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 ﷺ said to him, "Take off your shirt and wash off this yellowness and do in umra as you would do on hajj."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ حُمَيْدِ بْنِ قَيْسٍ، عَنْ عَطَاءِ بْنِ أَبِي رَبَاحٍ، أَنَّ أَعْرَابِيًّا، جَاءَ إِلَى رَسُولِ اللَّهِ ﷺ وَهُوَ بِحُنَيْنٍ وَعَلَى الأَعْرَابِيِّ قَمِيصٌ وَبِهِ أَثَرُ صُفْرَةٍ فَقَالَ يَا رَسُولَ اللَّهِ إِنِّي أَهْلَلْتُ بِعُمْرَةٍ فَكَيْفَ تَأْمُرُنِي أَنْ أَصْنَعَ فَقَالَ لَهُ رَسُولُ اللَّهِ ﷺ " انْزِعْ قَمِيصَكَ وَاغْسِلْ هَذِهِ الصُّفْرَةَ عَنْكَ وَافْعَلْ فِي عُمْرَتِكَ مَا تَفْعَلُ فِي حَجِّكَ " .