Exodus 13:5

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. Thus the Lord formally instituted the Feast of Unleavened Bread, with the usual detailed description of the Land of Promise and the corresponding reference to the fruitfulness of this country.