مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2701
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas (رضي الله عنه) said: The Messenger of Allah (ﷺ) said: “The best number for companionship is four, the best number for an expedition is four hundred and the best number for an army is four thousand.” And the Messenger of Allah (ﷺ) said: "People will never be defeated due to being too few in number if their number reaches twelve thousand.”
Musnad Ahmad 2718Hasan because of corroborating evidence; this is a da'eef is