مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3774
Musnad of Abdullah bin Mas'ood
It was narrated from 'Abdullah (رضي الله عنه) that He was in the mosque, offering supplication, when the Prophet (ﷺ) came in whilst he was offering supplication and he said: "Ask, you will be given," when he was saying: O Allah, I ask You for faith that does not waver, blessing that does not end and to accompany the Prophet (ﷺ) in the highest station in Paradise, the Paradise of eternity.
Musnad Ahmad 3797Saheeh because of corroborating evidence, this is a da’eef i