Bulugh al-Maram 8 Marriage كتاب النكاح 147

وَعَنِ اِبْنِ عَبَّاسٍ رَضِيَ اَللَّهُ عَنْهُمَا قَالَ: { كَانَ إِيلَاءُ اَلْجَاهِلِيَّةِ اَلسَّنَةَ وَالسَّنَتَيْنِ, فَوَقَّتَ اَللَّهُ أَرْبَعَةَ أَشْهُرٍ, فَإِنْ كَانَ أَقَلَّ مِنْ أَرْبَعَةِ أَشْهُرٍ, فَلَيْسَ بِإِيلَاءٍ } أَخْرَجَهُ اَلْبَيْهَقِيُّ . 1 . 1 – صحيح. رواه البيهقي (7 /381).

Narrated Ibn ‘Abbas (RA): The swearing to stay away from one’s wife in al-Jahiliyyah era was for one or two years. Then, Allah appointed a period of four months for it. So, if it is less than four months, it is not swearing to stay away from one’s wife. [al-Baihaqi reported it]