Jamieson, Fausset and Brown on Exodus 29:38

Ex 29:38-46. Institution of Daily Service.

38. two lambs of the first year day by day continually--The sacred preliminaries being completed, Moses was instructed in the end or design to which these preparations were subservient, namely, the worship of God; and hence the institution of the morning and evening sacrifice. The institution was so imperative, that in no circumstances was this daily oblation to be dispensed with; and the due observance of it would secure the oft-promised grace and blessing of their heavenly King.