أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا مُحَمَّدٌ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنِ الْحَكَمِ، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عَبَّاسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ هَذِهِ عُمْرَةٌ اسْتَمْتَعْنَاهَا فَمَنْ لَمْ يَكُنْ عِنْدَهُ هَدْىٌ فَلْيَحِلَّ الْحِلَّ كُلَّهُ فَقَدْ دَخَلَتِ الْعُمْرَةُ فِي الْحَجِّ ‏"‏ ‏.‏

It was narrated from Ibn Abbas that the Prophet said: This is 'Umrah that we have benefited from. Whoever does not have a Hadi with him, let him exit Ihram completely. Now 'Umrah is permissible during the months of Hajj." Translation Not Available

Book Ref: Sunan An Nisai Book 24 Hadith 2815
Web Ref:  Sunan An Nisai Vol 3 Book 24 Hadith 2817