Sayyiduna Atiyyah al-Qurazi (may Allah be pleased with him) said: On the day of Qurayzah I was presented before the Messenger of Allah (peace and blessings be upon him), and they were in doubt about me. The Messenger of Allah (peace and blessings be upon him) ordered: "Look at his pubic hair, whether it has grown or not." They looked at me and the hair had not grown, so they let me go and added me to the captives.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحجر / 11316