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.”