In chapter 13, the LORD sat apart the firstborn to Himself. He had just preserved their lives by passing over the houses with the blood on the door frame in the tenth plague. As a result, the firstborn belonged to Him. The LORD also gave laws concerning the firstborn and the Feast of Unleavened Bread when the Israelites inhabit the Promised Land. After this was established, the Israelites began their exodus from Egypt to go to the land the LORD had promised them.
Chapter 13 can be outlined as follows:
The first sixteen verses are somewhat repetitive to what has been said in previous chapters. The repetition is employed here by the LORD to emphasize the importance of these concepts. Verses 1 – 2 contain the LORD’s command to set apart the firstborn to Him. Verses 3 – 10 repeat the rules for observing the feast of Unleavened Bread. Then verses 11 – 16 provide additional instruction concerning the firstborn. There are also rules laid out for celebrating both the Passover and the Feast of Unleavened Bread.
The Lord commands Israel to set apart the firstborn of all people and animals to His service.
The Lord gives commands regarding the annual festival of Unleavened Bread and Passover.
Verses 11 – 16 contain the LORD’s instructions dealing with the firstborn.
This section (verses 17 – 22) describes the beginning of the journey from Egypt to the Red Sea. It stresses that the LORD led them with a pillar of cloud or fire. He chose a route to the Red Sea for a specific purpose. The point is also made that Moses made sure that Joseph’s bones were carried with them.