Salamah bin Sakhr Bayadhi (may Allah be pleased with him) narrates that the Prophet Muhammad (peace and blessings be upon him) regarding a person who performs intercourse before paying the expiation for zihar, said: "There is only one expiation upon him."
Hadith Referenceسنن ابن ماجه / كتاب الطلاق / 2064
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:ضعيف, ضعيف, انظر الحديث السابق (2062), انوار الصحيفه، صفحه نمبر 452
´It was narrated from Ibn 'Abbas that:` a man declared Zihar upon his wife, then he had intercourse with her before offering expiation. He came to the Prophet (ﷺ) and told him about that. He said: "What made you do that?" He said: "I saw her ankles in the moonlight, and I could not control myself, and I had intercourse with her." The Messenger of Allah (ﷺ) smiled and told him not to go near her until he had offered expiation.
Hadith Referenceسنن ابن ماجه / كتاب الطلاق / 2065
Hadith Gradingالألبانی:حسن | زبیر علی زئی:إسناده حسن
Hadith Takhrij« سنن ابی داود/الطلاق 17 ( 2223 ) ، سنن الترمذی/الطلاق 19 ( 1199 ) ، سنن النسائی/الطلاق 33 ( 3487 ) ، ( تحفة الأشراف : 6036 ) ( حسن ) » ( سند میں حکم بن ابان ضعیف الحفظ ہیں ، لیکن شواہد کی وجہ سے یہ حسن ہے )