Al-Hakam bin Aban narrates from Ikrimah (may Allah have mercy on him) that a man made zihar from his wife and then had intercourse with her before offering the expiation. Then he came to the Prophet (peace and blessings be upon him) and told him. He (peace and blessings be upon him) asked: "What prompted you (to do this)?" He said: I saw her white shin on a moonlit night. He (peace and blessings be upon him) said: "Keep away from her until you have offered the expiation."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الظهار / 15261