"And it shall be, when the LORD brings you into the land of the Canaanites, as He swore to you and your fathers, and gives it to you, that you shall set apart to the LORD all that open the womb, that is, every firstborn that comes from an animal which you have; the males shall be the LORD's. But every firstborn of a donkey you shall redeem with a lamb; and if you will not redeem it, then you shall break its neck. And all the firstborn of man among your sons you shall redeem. So it shall be, when your son asks you in time to come, saying, 'What is this?' that you shall say to him, 'By strength of hand the LORD brought us out of Egypt, out of the house of bondage. And it came to pass, when Pharaoh was stubborn about letting us go, that the LORD killed all the firstborn in the land of Egypt, both the firstborn of man and the firstborn of beast. Therefore I sacrifice to the LORD all males that open the womb, but all the firstborn of my sons I redeem.' It shall be as a sign on your hand and as frontlets between your eyes, for by strength of hand the LORD brought us out of Egypt" (Exo. 13:11-16).
Here God elaborates on what is expected of any firstborn male creatures (human or animal) that opens the womb (apparently the females were exempt). If the animal was suitable to be sacrificed, then that was expected. However, not all firstborn creatures were appropriate for sacrifice (e.g., donkeys and humans). In the case of a donkey (or any unclean animal), the owner had two options: (1) Sacrifice a lamb in place of the donkey (i.e., "redeem it") or (2) Break the donkey's neck (thus, taking its life, which belonged to God anyway). In the case of human males, there was no choice; they had to be redeemed (which underscores the sanctity of human life in God's eyes, which is not surprising since He has made us in His image; cf. Gen. 1:26,27). So, what exactly does it mean to redeem a human for the LORD? Since all firstborn were God's, to redeem a human was to buy him back (in other words, spare his life for a price). Some have speculated that God's initial intent was for the firstborn males to serve God in both priestly and non-priestly roles for the nation (cf. Exo. 19:5,6; Num. 3:12,13,40-51; 18:14-20). Thus, their redemption price would be service in exchange for their existence. But, this never came to fruition. Instead, all of the Levite males were assigned this role instead of the firstborn males of the entire nation. In the case where a Levite was not substituted for a firstborn, five shekels was paid to God as the redemption price. All of this was to be taught and reiterated to the children regularly. For Christians today, Romans 12:1 and I Peter 2:9 come to mind. All Christians are priests and are to present themselves as living sacrifices for the service of God.
"Then it came to pass, when Pharaoh had let the people go, that God did not lead them by way of the land of the Philistines, although that was near; for God said, 'Lest perhaps the people change their minds when they see war, and return to Egypt.' So God led the people around by way of the wilderness of the Red Sea. And the children of Israel went up in orderly ranks out of the land of Egypt. And Moses took the bones of Joseph with him, for he had placed the children of Israel under solemn oath, saying, 'God will surely visit you, and you shall carry up my bones from here with you'" (Exo. 13:17-19).
The people left Egypt in an orderly or well-arranged manner. God was leading the people the long way, but it was the best way for them to go. There is a good lesson in this for us today: God's way is always right and best, though it may not always seem that way from our perspective (cf. Prov. 3:5-7). Joseph's bones were not forgotten in the rush of the exodus. Moses fulfilled the oath the children of Israel had made to Joseph.
"So they took their journey from Succoth and camped in Etham at the edge of the wilderness. And the LORD went before them by day in a pillar of cloud to lead the way, and by night in a pillar of fire to give them light, so as to go by day and night. He did not take away the pillar of cloud by day or the pillar of fire by night from before the people" (Exo. 13:20-22). Their journey to freedom has begun and God's presence is with them always, providing guidance, illumination, and protection.