مُسْنَدُ أَحْمَدَ
Musnad Ahmad 4109
Musnad of Abdullah bin Mas'ood
It was narrated that ‘Abdullah said: The Messenger of Allah (ﷺ) said: “If I were to have taken a close friend (khaleel) I would have taken Ibn Abi Quhafah (Abu Bakr) as a close friend.”
Musnad Ahmad 4136Its isnad is saheeh, Muslim (2383)]