Is expiation (kaffarah) for menstruation obligatory for one who commits adultery with a menstruating woman, or is repentance sufficient for him?

Adultery is a grave sin and one of the major transgressions. Whoever is afflicted by it should conceal themselves with Allah's veil and hasten to sincere repentance by abandoning it, regretting it, and resolving never to return to it. There is no expiation required for intercourse during menstruation according to the majority of scholars, but giving it out is more cautious.