كتاب النكاح
16  
The Book of Marriage
(5)
Chapter: The prohibition of marriage for one who is in Ihram, and it is disliked for him to propose marriage
(5)
باب تَحْرِيمِ نِكَاحِ الْمُحْرِمِ وَكَرَاهَةِ خِطْبَتِهِ ‏‏
Sahih Muslim 1409 b

Nubaih b. Wahb reported:

Umar b. Ubaidullah b. Ma'mar sent me to Aban b. Uthman as he wanted to make the proposal of the marriage of his son with the daughter of Shaiba b. Uthman. He (Aban b. Uthman) was at that time (busy) in the season of Pilgrimage. He said: I deem him to be a man of the desert (for it is a common thing) that a Muhrim can neither marry, nor is he allowed to be married to anyone. It is Uthman (b. Affan) who reported this to us from Allah's Messenger (ﷺ).
وَحَدَّثَنَا مُحَمَّدُ بْنُ أَبِي بَكْرٍ الْمُقَدَّمِيُّ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، حَدَّثَنِي نُبَيْهُ بْنُ وَهْبٍ، قَالَ بَعَثَنِي عُمَرُ بْنُ عُبَيْدِ اللَّهِ بْنِ مَعْمَرٍ وَكَانَ يَخْطُبُ بِنْتَ شَيْبَةَ بْنِ عُثْمَانَ عَلَى ابْنِهِ فَأَرْسَلَنِي إِلَى أَبَانِ بْنِ عُثْمَانَ وَهُوَ عَلَى الْمَوْسِمِ فَقَالَ أَلاَ أُرَاهُ أَعْرَابِيًّا ‏ "‏ إِنَّ الْمُحْرِمَ لاَ يَنْكِحُ وَلاَ يُنْكَحُ ‏"‏ ‏.‏ أَخْبَرَنَا بِذَلِكَ عُثْمَانُ عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏
Reference : Sahih Muslim 1409b
In-book reference : Book 16, Hadith 50
USC-MSA web (English) reference : Book 8, Hadith 3279
  (deprecated numbering scheme)