זוהר שמות — דף מא ע”ב

The Destroyer is the one who killed the firstborn of Egypt, while the Holy One Himself killed the firstborn of holiness through the Destroyer's hand. It is forbidden to break bones in the Passover offering so as not to disgrace Egypt's idols. The sanctification of the firstborn is given to God in response to what God did for Israel at the Exodus, and it is the consecration of the first fruits of all things.