Hadith #2168 (Sunan Abi Dawud)
Book: Marriage (Kitab Al-Nikah)
Narrator(s): Abd al-Salam bin Mthr عبد السلام بن مطهر بن حسام, Ali bin al-Hakam al-Binani علي بن الحكم البناني, ibn Abbas, Ja'far bin Sulaiman al-Daba'i جعفر بن سليمان الضبعي, Maqsim bin Bajra مقسم بن بجرة
Grade: Sahih

The Prophet (ﷺ) said about a man who has sexual intercourse with a menstruating woman: He should give one or half dinar as sadaqah.

Source: https://parallelquran.com/hadith/sunan-abi-dawud-2168/