Sahih Muslim 1409
Sahih Muslim · Book 16: The Book of Marriage · The prohibition of marriage for one who is in Ihram, and it is disliked for him to propose marriage
Nabaih b. Wahb reported that Umar b. 'Ubaidullah b. Ma'mar intended to marry his son Talha with the daughter of Shaiba b. Jubair during the Pilgrimage. Aban b. Uthman was at that time the Amir of Pilgrims. So he ('Umar b. Ubaidullah) sent someone (as a messenger) to Aban saying:
حَدَّثَنَا عَبْدُ الْمَلِكِ بْنُ شُعَيْبِ بْنِ اللَّيْثِ ، حَدَّثَنِي أَبِي ، عَنْ جَدِّي ، حَدَّثَنِي خَالِدُ بْنُ يَزِيدَ ، حَدَّثَنِي سَعِيدُ بْنُ أَبِي هِلاَلٍ ، عَنْ نُبَيْهِ بْنِ وَهْبٍ ، أَنَّ عُمَرَ بْنَ عُبَيْدِ اللَّهِ بْنِ مَعْمَرٍ، أَرَادَ أَنْ يُنْكِحَ، ابْنَهُ طَلْحَةَ بِنْتَ شَيْبَةَ بْنِ جُبَيْرٍ فِي الْحَجِّ وَأَبَانُ بْنُ عُثْمَانَ يَوْمَئِذٍ أَمِيرُ الْحَاجِّ فَأَرْسَلَ إِلَى أَبَانٍ إِنِّي قَدْ أَرَدْتُ أَنْ أُنْكِحَ، طَلْحَةَ بْنَ عُمَرَ فَأُحِبُّ أَنْ تَحْضُرَ، ذَلِكَ . فَقَالَ لَهُ أَبَانٌ أَلاَ أُرَاكَ عِرَاقِيًّا جَافِيًا إِنِّي سَمِعْتُ عُثْمَانَ بْنَ عَفَّانَ يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ يَنْكِحُ الْمُحْرِمُ " .
I intend to marry Talha b. 'Umar and I earnestly desire you to be present there (in this ceremony of marriage). Aban said to him: I find you a block-headed 'Iraqi. I heard 'Uthman b. 'Affan say that Allah's Messenger (ﷺ) said: A Muhrim should not marry.