It is narrated from Ata (may Allah have mercy on him) that Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: Whoever has intercourse with his wife during her menstruation will give one dinar in charity.
Hadith Referenceسنن دارمي / من كتاب الطهارة / 1154
Hadith Takhrijاس اثر کی سند ضعیف ہے، اور موقوف بھی ہے۔ پیچھے تخریج گذر چکی ہے۔
Brief Explanation
(Commentary on Ahadith 1141 to 1154)
The summary of all these narrations is that engaging in intercourse during menstruation (hayd) is a sin and one should seek forgiveness and repent. It is better, though not obligatory, to give one dinar or half a dinar in charity. The value of one dinar in this era is approximately 20 Saudi riyals, and at present, one riyal is about 18 Indian rupees and 40 Pakistani rupees. Thus, the value of twenty riyals is 360 Indian rupees, and the value of one dinar in Pakistani rupees at this time is 800 rupees. And Allah knows best. For details, see: [المجموع 259/2], [المحلى و التلخيص 161/1], and [نيل الأوطار 351/1].