When the demand for Israel's release had been first presented to the king of Egypt, the warning of the most terrible of the plagues had been given. Moses was directed to say to Pharaoh, "Thus saith the Lord, Israel is My son, even My first-born: and I say unto thee, Let My son go, that he may serve Me: and if thou refuse to let him go, behold, I will slay thy son, even thy first-born." Exodus 4:22, 23. Though despised by the Egyptians, the Israelites had been honored by God, in that they were singled out to be the depositaries of His law. In the special blessings and privileges accorded them, they had pre-eminence among the nations, as the first-born son had among brothers.

Dette kapitel er bygget op over 2 Mos 11; 12,1-32
Da kravet om Israels frigivelse blev fremsat over for Ægyptens konge første gang, blev han samtidig advaret om den frygteligste af alle plagerne. Moses havde fået befaling om at sige til Farao: "Israel er min førstefødte søn; men da jeg sagde til dig: Lad min søn rejse, for at han kan dyrke mig! da nægtede du at lade ham rejse. Se, jeg dræber din førstefødte søn!" 2. Mos. 4, 22-23. Skønt israelitterne blev foragtet af ægypterne, havde Gud æret dem ved at vælge dem til at opbevare sin lov. De særlige velsignelser og forrettigheder, der var tildelt dem, indbefattede, at de havde samme forrang frem for andre folk, som den førstefødte havde frem for sine brødre.