And it shall be when the LORD shall bring thee into the land of the Canaanites, and the Hittites, and the Amorites, and the Hivites, and the Jebusites, which he sware unto thy fathers to give thee, a land flowing with milk and honey, that thou shalt keep this service in this month. When the Lord shall bring thee into the land - Hence it is pretty evident that the Israelites were not obliged to celebrate the Passover, or keep the feast of unleavened bread, till they were brought into the promised land.
Related Commentaries of Exodus 13:5
Exodus 13:5
5 And it shall be when the LORD shall bring thee into the land of the Canaanites, and the Hittites, and the Amorites, and the Hivites, and the Jebusites, which he sware unto thy fathers to give thee, a land flowing with milk and honey, that thou shalt keep this service in this month.