Sunan Abi Dawud, Hadith 2222

Ibn ‘Umar said “The waiting period of a woman who separates herself from her husband for compensation is a menstrual period.”

حَدَّثَنَا الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ عِدَّةُ الْمُخْتَلِعَةِ حَيْضَةٌ ‏.‏

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also referenced under: Hadith 2230 (DarusSalam)