كتاب النكاح
13  
Marriage
(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