(31) باب جَوَازِ الْعُمْرَةِ فِي أَشْهُرِ الْحَجِّ
Ibn 'Abbas (Allah be pleased with them) 'is reported to have said:
The Messenger of Allah (ﷺ) put on Ihigm for Hajj. When four days of Dhu'l-Hijja were over, he led the dawn prayer, and when the prayer was complete, he said: He who wants to change it to Umra may do so.
Reference: Sahih Muslim 1240 b
In-book reference: Book 15, Hadith 218
USC-MSA web (English) reference(deprecated numbering scheme): Book 7, Hadith 2859