كتاب الطهارة
1  
The Book of Purification
(182)
Chapter: What Is required Of A Person Who Had Intercourse With A Woman Of His During Her Period, After He Came to know that Allah has prohibited that
(182)
باب مَا يَجِبُ عَلَى مَنْ أَتَى حَلِيلَتَهُ فِي حَالِ حَيْضَتِهَا بَعْدَ عِلْمِهِ بِنَهْىِ اللَّهِ عَزَّ وَجَلَّ عَنْ وَطْئِهَا
Sunan an-Nasa'i 289
It was narrated from Ibn 'Abbas from the Prophet (ﷺ) concerning a man who has had intercourse while she was menstruating:
"Let him give a Dinar or half a Dinar in charity."
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ شُعْبَةَ، عَنِ الْحَكَمِ، عَنْ عَبْدِ الْحَمِيدِ، عَنْ مُقْسَمٍ، عَنِ ابْنِ عَبَّاسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم فِي الرَّجُلِ يَأْتِي امْرَأَتَهُ وَهِيَ حَائِضٌ يَتَصَدَّقُ بِدِينَارٍ أَوْ بِنِصْفِ دِينَارٍ ‏.‏
Grade: Sahih (Darussalam)
Reference : Sunan an-Nasa'i 289
In-book reference : Book 1, Hadith 290
English translation : Vol. 1, Book 1, Hadith 290