Abd al-Hamid bin Ja'far narrates through his father that the father of Sayyiduna Samurah bin Jundub (may Allah be pleased with him) passed away, leaving behind his son Samurah. She (Samurah's mother) was a beautiful woman. She came to Madinah, and proposals of marriage came to her, and she began to say: "I will not marry any man except one who takes responsibility for the maintenance of her son Samurah until he reaches maturity." So a man from the Ansar married her on that condition, and she (Samurah's mother) began living with him among the Ansar.
The Prophet (peace and blessings be upon him) used to inspect the boys of the Ansar every year (for maturity), and whoever among them had reached maturity, he (peace and blessings be upon him) would send him with the army (for jihad). One year he (peace and blessings be upon him) inspected them, and a boy passed before him (peace and blessings be upon him), so he (peace and blessings be upon him) sent him with the army. Then Samurah was presented after him, and he (peace and blessings be upon him) sent him back. Samurah said: "O Messenger of Allah, you accepted a boy and sent me back, although if he wrestled with me I would throw him down?" He (peace and blessings be upon him) said: "Very well, then wrestle with him." He said: "I threw him down, so he (peace and blessings be upon him) included me in the army."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6719