صَحِيحُ مُسْلِمٍ
Sahih Muslim 1240 e
The Book of Pilgrimage
It is permissible to perform 'Umrah during the months of Hajj
وَحَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ أَيُّوبَ، عَنْ أَبِي الْعَالِيَةِ، عَنِ ابْنِ عَبَّاسٍ، - رضى الله عنهما - قَالَ صَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم الصُّبْحَ بِذِي طَوًى وَقَدِمَ لأَرْبَعٍ مَضَيْنَ مِنْ ذِي الْحِجَّةِ وَأَمَرَ أَصْحَابَهُ أَنْ يُحَوِّلُوا إِحْرَامَهُمْ بِعُمْرَةٍ إِلاَّ مَنْ كَانَ مَعَهُ الْهَدْىُ .
Ibn Abbas (Allah be pleased with them) reported that Allah's Messenger (ﷺ) observed the morning prayer at Dhu Tawa (a valley near Mecca) and arrived (in Mecca) when four days of Dhul-Hijja had passed and he commanded his Companions that they should change their Ihram (of Hajj) to that of Umra, except those who had brought sacrificial animals with them.
Sahih Muslim, 1240 eSahihصحيح