What is the ruling on departing Muzdalifah after sunrise on the Day of Sacrifice (Yawm al-Nahr), and is there any expiation (fidyah) or blood sacrifice (dam) due for one who does so?

The Sunnah is to depart from Muzdalifah before sunrise, as the Prophet, peace and blessings be upon him, did. Whoever departs after sunrise has gone against the Sunnah, but nothing is incumbent upon them if they have performed the obligatory rites. There is no scholar who has mandated a fidyah (expiation) for that.