Command the children of Israel, and say unto them, My offering, and my bread for my sacrifices made by fire, for a sweet aroma unto me, shall you observe to offer unto me in their due season.
Read Chapter 28
Ambrose of Milan
This is indeed a full and perfect sacrifice, as the Lord tells us in speaking of gifts and contributions as his: “You will offer to me my oblation in my festal days,” sparing nothing and setting nothing aside, but offering a full, complete and perfect sacrifice. By “festal day” is meant the Lord’s Day, a time appropriate to acts of perfect virtue. These acts are made perfect if our souls quell the anxieties of this world and the enticements of the flesh in a victorious struggle over hedonism. Thus the soul is free from the world and dedicated to God, departing not even in the slightest way from the path of good intentions and casting aside all distractions, whether of pleasure or of toil. The wise— and no one else—celebrate with due solemnity this festal day. . ...
Seasons. These precepts had often been repeated already: but perhaps they had not been exactly observed in the desert, so that Moses inculcates them once more, as if to remind the people that they will now have no excuse, if they neglect these sacrifices in the promised land. (Calmet)
These frequent repetitions may also remind us, with what attention we ought to worship God. (Du Hamel) ...