مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2788
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas (رضي الله عنه) that the Prophet (ﷺ) said: ‘Umrah in Ramadan is equivalent to Hajj.”
Musnad Ahmad 2808A saheeh hadeeth; this is a da'eef isnad]