مُسْنَدُ أَحْمَدَ
Musnad Ahmad 4326
Musnad of Abdullah bin Mas'ood
It was narrated that 'Abdullah bin Mas'ood (رضي الله عنه) said: After the verse "When there comes the Help of Allah (to you, O Muhammad (ﷺ)) against your enemies) and the Conquest (of Makkah)" (an-Nasr 110:1) was revealed, the Prophet (ﷺ) would often say: “Glory and praise be to You, O Allah. O Allah, forgive me, for You are the Acceptor of repentance. O Allah forgive me; glory and praise be to You, O Allah. O Allah forgive me, glory and praise be to You, O Allah."
Musnad Ahmad 4356Hasan because of corroborating evidence, its isnad is da'eef