Sunan Ibn Majah, Volume 4, Book 25, Hadith 2993 (DarusSalam) ⓘ
It was narrated from Abu Ma’qil that the Prophet said: “ ‘Umrah during Ramadan is equivalent to Hajj.”
حَدَّثَنَا جُبَارَةُ بْنُ الْمُغَلِّسِ، حَدَّثَنَا إِبْرَاهِيمُ بْنُ عُثْمَانَ، عَنْ أَبِي إِسْحَاقَ، عَنِ الأَسْوَدِ بْنِ يَزِيدَ، عَنْ أَبِي مَعْقِلٍ، عَنِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قَالَ " عُمْرَةٌ فِي رَمَضَانَ تَعْدِلُ حِجَّةً " .
also referenced under: Hadith 2993 (Reference) & Book 25, Hadith 3107 (In-Book)