A man came to the Prophet of Allah ﷺ and said, "Prophet of Allah, I declared zihar against my wife, then I had relations with her before fulfilling what was due upon me."He asked, "What led you to do that?"The man replied, "Prophet of Allah, I saw the whiteness of her legs in the moonlight."The Prophet of Allah ﷺ said, "Then keep away from her until you have fulfilled what is due upon you."In Ishaq's version, the wording is, "Keep away from her until you have fulfilled what is due upon you." The wording belongs to Muhammad.Abu Abdul-Rahman said, The mursal version is more likely correct than the musnad, and Allah knows best.
أخبرنا إسحق بن إبراهيم قال أنبأنا المعتمر ح وأنبأنا محمد بن عبد الأعلى قال حدثنا المعتمر قال سمعت الحكم بن أبان قال
أتى رجل نبي الله ﷺ فقال يا نبي الله إنه ظاهر من امرأته ثم غشيها قبل أن يفعل ما عليه قال ما حملك على ذلك قال يا نبي الله رأيت بياض ساقيها في القمر قال نبي الله ﷺ فاعتزل حتى تقضي ما عليك وقال إسحق في حديثه فاعتزلها حتى تقضي ما عليك واللفظ لمحمد قال أبو عبد الرحمن المرسل أولى بالصواب من المسند والله سبحانه وتعالى أعلم
[Its isnad is hasan] See the two preceding hadiths. It is in Kubra, no. 5653.