It is narrated from Sayyiduna Miqsam bin Bujrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) placed him in charge of the captives of Banu Qurayzah. He would look at the private part of a boy: if pubic hair had grown on it, his neck was struck, and if it had not grown, he was placed among the spoils of the Muslims.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17105