Musannaf Ibn Abi Shayba 9:1392

Ibn Idris narrated to us, from Muhammad ibn ‘Ajlan, from Nafi’, from Ibn ‘Umar, who said: A private part is not lawful except through ownership or marriage. And if he divorces, it is permissible; and if he emancipates, it is permissible; and if he gifts, it is permissible.