Musnad Ahmad 652:98

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Abu Bishr, from Khalid ibn ‘Arfatah, from Habib ibn Salim, from al-Nu‘man ibn Bashir, from the Prophet, may Allah bless him and grant him peace, that he said regarding a man who comes to his wife’s slave-girl: "If she had made her lawful for him, I would flog him one hundred times. And if she had not made her lawful for him, I would stone him."