Exodus 3:18 first records the command to request a three-day journey—now repeated as the consistent divine demand to let Israel serve God.

Exodus 4:22 introduces the same 'Thus says the LORD' formula and identifies Israel as God's firstborn—the basis for the demand.

Exodus 4:23 contains the identical demand 'Let my son go that he may serve me'—here applied to the whole people.

Exodus 5:1 is the first fulfillment of this command when Moses and Aaron actually deliver it to Pharaoh.

Exodus 8:1 has the exact same command for the plague of frogs—showing this pattern repeated for each plague.

Exodus 8:20 repeats this command for the plague of flies, with the added detail of meeting Pharaoh at the water.

Exodus 10:3 includes a rebuke 'How long will you refuse to humble yourself?' before the same demand—highlighting Pharaoh's hardness.

Exodus 7:16 is the first occurrence of this demand, for the plague of blood—the initial warning to Pharaoh.