Roast with fire. — Roasting is the simplest, the easiest, and the most primitive mode of cooking meat. It was also the only mode open to all the Hebrews, since the generality would not possess cauldrons large enough to receive an entire lamb. Further, the requirement put a difference between this and other victims, which were generally cut up and boiled (1 Samuel 2:14-15).
Unleavened bread... bitter herbs. — As partaking of the lamb typified feeding on Christ, so the putting away of leaven and eating unleavened bread signified the putting away of all defilement and corruption ere we approach Christ to feed on Him (1 Corinthians 5:8). As for the bitter herbs, they probably represented “self-denial” or “repentance” — fitting concomitants of the holy feast, where the Lamb of God is our food. At any rate, they were a protest against that animalism which turns a sacred banquet into a means of gratifying the appetite (1 Corinthians 11:20-22).