مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3486
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn '‘Abbas (رضي الله عنه) that he said: The Messenger of Allah (ﷺ) entered ihram for Hajj and came on the fifth of Dhul-Hijjah and led us in Fajr prayer in al-Batha', then he said: "Whoever would like to make it 'Umrah, let him do so."
Musnad Ahmad 3509Its isnad is saheeh, al-Bukhari (1085) and Muslim (1240)]