It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that we used to participate in battles with the Prophet (peace and blessings of Allah be upon him); we were young and there were no women with us. Once we said: O Messenger of Allah (peace and blessings of Allah be upon him)! Should we not get ourselves castrated? The Prophet (peace and blessings of Allah be upon him) forbade us from doing so.