Others say: I might think that if a firstling passed its time (for sacrifice) from one year to the next it would be invalidated as are the (other) offerings (in such an instance); it is, therefore, written "And you shall eat … the tithe … and the firstlings." A firstling is being compared to second-tithe, viz.: Just as second-tithe is eaten from one year to the next, so, a firstling.
(Ibid.) "so that you learn to fear the L-rd your G-d": We are hereby taught that the act leads to fear. "all of the days": both weekdays and Sabbath.