A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown [1882] at sacred-texts.com
Command the children of Israel, and say unto them--The repetition of several laws formerly enacted, which is made in this chapter, was seasonable and necessary, not only on account of their importance and the frequent neglect of them, but because a new generation had sprung up since their first institution and because the Israelites were about to be settled in the land where those ordinances were to be observed.
My offering, and my bread--used generally for the appointed offerings, and the import of the prescription is to enforce regularity and care in their observance.
This is the burnt offering of every sabbath--There is no previous mention of a Sabbath burnt offering, which was additional to the daily sacrifices.
And in the beginnings of your months ye shall offer a burnt offering unto the Lord--These were held as sacred festivals; and though not possessing the character of solemn feasts, they were distinguished by the blowing of trumpets over the sacrifices (Num 10:10), by the suspension of all labor except the domestic occupations of women (Amo 8:5), by the celebration of public worship (Kg2 4:23), and by social or family feasts (Sa1 20:5). These observations are not prescribed in the law though they obtained in the practice of a later time. The beginning of the month was known, not by astronomical calculations, but, according to Jewish writers, by the testimony of messengers appointed to watch the first visible appearance of the new moon; and then the fact was announced through the whole country by signal-fires kindled on the mountain tops. The new-moon festivals having been common among the heathen, it is probable that an important design of their institution in Israel was to give the minds of that people a better direction; and assuming this to have been one of the objects contemplated, it will account for one of the kids being offered unto the Lord (Num 28:15), not unto the moon, as the Egyptians and Syrians did. The Sabbath and the new moon are frequently mentioned together.
in the fourteenth day of the first month is the passover--The law for that great annual festival is given (Lev 23:5), but some details are here introduced, as certain specified offerings are prescribed to be made on each of the seven days of unleavened bread [Num 28:18-25].
in the day of the first-fruits . . . offer the burnt offering--A new sacrifice is here ordered for the celebration of this festival, in addition to the other offering, which was to accompany the first-fruits (Lev 23:18).