We have the unleavened bread, and the first-born consecrated, as the consequence and result of deliverance from Egypt, i.e., separation (consecration) to God in the double sense of purity, unfeignedness of heart, and complete devotedness. These are the fruit of having to say to God in the way of divine power in deliverance—the result of the sense of it—note this.
This is brought in, in testimony, before the Red Sea.
Note too, the connection of unleavened bread and consecration of first-born on common ground here; both as a memorial in the land—the double character of the moral result looked for (produced by grace) in those delivered.
18. I think the force of khamushim (harnessed) is evident enough—they did not fly away individually, though they went in haste—it was Jehovah b'yad khazakah (with a strong hand) did it.