(13) Marriage
كتاب النكاح
(11a) Chapter: Separating from a Wife for a Compensation ; and Divorce - Section 1
(11) باب الخلع والطلاق
Mishkat al-Masabih 3277 
Ibn ‘Abbas said:
One makes atonement for something he has made unlawful for himself.* You have had a good example in God’s Messenger. * i.e. something not in itself unlawful. It is treated like an oath for breaking which atonement must be made. The Prophet’s example refers to his withdrawing from his wives for a period. (Bukhari and Muslim.)
وَعَنِ ابْنِ عَبَّاسٍ قَالَ: فِي الْحَرَامِ يُكَفَّرُ لَقَدْ كَانَ لَكُمْ فِي رَسُولِ الله أُسْوَة حَسَنَة
 مُتَّفَقٌ عَلَيْهِ  (الألباني)حكم :
Reference : Mishkat al-Masabih 3277
In-book reference : Book 13, Hadith 193