It wasnarrated from Anas bin Malik that the Messenger of Allah (ﷺ)saidto Aktham bin Al-Jawn Al-Khuza'i:
"O Aktham! Fight alongsidepeople other than your own, it will improve your attitude and makeyougenerous to your companions. O Aktham, the best number ofcompanionsis four, the best number of troops on an expedition isfour hundred,the best number of an army is four thousand, and twelvethousand willnever be overpowered because of their small number."
English reference: Vol. 4, Book 24, Hadith 2827
Arabic reference: Book 24, Hadith 2934