ENOfficial
Narrated Abdullah ibn Abbas: If a man has sexual intercourse (with menstruating woman) during her bleeding, he should give one dinar as sadaqah, and if he does so when bleeding has stopped, he should give half a dinar as sadaqah.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَبْدُ السَّلاَمِ بْنُ مُطَهَّرٍ، حَدَّثَنَا جَعْفَرٌ، - يَعْنِي ابْنَ سُلَيْمَانَ - عَنْ عَلِيِّ بْنِ الْحَكَمِ الْبُنَانِيِّ، عَنْ أَبِي الْحَسَنِ الْجَزَرِيِّ، عَنْ مِقْسَمٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ إِذَا أَصَابَهَا فِي الدَّمِ فَدِينَارٌ وَإِذَا أَصَابَهَا فِي انْقِطَاعِ الدَّمِ فَنِصْفُ دِينَارٍ .
sunnah.com