مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3557
Musnad of Abdullah bin Mas'ood
It was narrated from `Abdullah (رضي الله عنه) from The Prophet (ﷺ) “I disavow the friendship of anyone who claims I am his close friend. If I were to have taken a close friend (khaleel) I would have taken Abu Bakr as a close friend, but your companion (meaning himself) is the close friend (khaleel) of Allah.”
Musnad Ahmad 3580Its isnad is saheeh, Muslim (2383)]