Jamieson, Fausset and Brown on Exodus 13:5-7

5-7. when the Lord shall bring thee--The passover is here instituted as a permanent festival of the Israelites. It was, however, only a prospective observance; we read of only one celebration of the passover during the protracted sojourn in the wilderness [Nu 9:5]; but on their settlement in the promised land, the season was hallowed as a sacred anniversary [Jos 5:10], in conformity with the directions here given.