It was narrated from Ibn 'Abbas from the Prophet (ﷺ) concerning a man who has had intercourse with his wife while she was menstruating:"Let him give a Dinar or half a Dinar in charity."
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ شُعْبَةَ، قَالَ حَدَّثَنِي الْحَكَمُ، عَنْ عَبْدِ الْحَمِيدِ، عَنْ مِقْسَمٍ، عَنِ ابْنِ عَبَّاسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم فِي الرَّجُلِ يَأْتِي امْرَأَتَهُ وَهِيَ حَائِضٌ يَتَصَدَّقُ بِدِينَارٍ أَوْ بِنِصْفِ دِينَارٍ .
Nesai
The Book of Menstruation and Istihadah • Hadith 370