Parading the Army
As soon as he reached a location called Ash-Shaikhan, he paraded his army. He dismissed those whom he considered to be disabled or too young to stand the fight. Among them were ‘Abdullah bin ‘Umar bin Al-Khattab. Usama bin Zaid; Usaid bin Zaheer, Zaid bin Thabit, Zaid bin Arqam. ‘Araba bin Aws, ‘Amr bin Hazm, Abu Sa‘eed Al-Khudri, Zaid bin Haritha Al-Ansari, Sa‘d bin Habba and Al-Barâ’ bin ‘Azib, Sahih Al-Bukhari pointed out that he had shared in the fight that day.
The Messenger of Allâh [pbuh] allowed both Rafi‘ bin Khadaij and Samura bin Jundub to join the army — though they were too young. The former proved to be skillful at shooting arrows; the latter wrestled the former and beat him. The admission of Rafi‘ made Samura say: "I am stronger than him, I can overcome him." When the Prophet [pbuh] heard this saying he ordered them to wrestle. They did. Samura won so he was also admitted.