Albert Barnes Commentary Numbers 15:22-31

"And when ye shall err, and not observe all these commandments, which Jehovah hath spoken unto Moses, even all that Jehovah hath commanded you by Moses, from the day that Jehovah gave commandment, and onward throughout your generations; then it shall be, if it be done unwittingly, without the knowledge of the congregation, that all the congregation shall offer one young bullock for a burnt-offering, for a sweet savor unto Jehovah, with the meal-offering thereof, and the drink-offering thereof, according to the ordinance, and one he-goat for a sin-offering. And the priest shall make atonement for all the congregation of the children of Israel, and they shall be forgiven; for it was an error, and they have brought their oblation, an offering made by fire unto Jehovah, and their sin-offering before Jehovah, for their error: and all the congregation of the children of Israel shall be forgiven, and the stranger that sojourneth among them; for in respect of all the people it was done unwittingly. And if one person sin unwittingly, then he shall offer a she-goat a year old for a sin-offering. And the priest shall make atonement for the soul that erreth, when he sinneth unwittingly, before Jehovah, to make atonement for him; and he shall be forgiven. Ye shall have one law for him that doeth aught unwittingly, for him that is home-born among the children of Israel, and for the stranger that sojourneth among them. But the soul that doeth aught with a high hand, whether he be home-born or a sojourner, the same blasphemeth Jehovah; and that soul shall be cut off from among his people. Because he hath despised the word of Jehovah, and hath broken his commandment, that soul shall utterly be cut off; his iniquity shall be upon him." — Numbers 15:22-31 (ASV)

The heavy punishments that had already overtaken the people might naturally give rise to apprehensions for the future, especially considering that on their approaching entrance into Canaan, the complete observance of the Law in all its details would become binding on them. To address such apprehensions, a distinction is emphatically drawn between sins of ignorance (Leviticus 4:13 and following) and those of presumption (Numbers 15:30–31). The passage deals separately with imperfections of obedience that would be regarded as pertaining to the whole nation (Numbers 15:22–26), and those of individuals (Numbers 15:27–30).

On Numbers 15:24: Without the knowledge of the congregation – literally, as the marginal note indicates. The words point to an error of omission which escaped notice at the time: that is, to an oversight.

On Numbers 15:30: Presumptuously – The original (compare the margin and Exodus 14:8) signifies something done willfully and openly; in the case of a sin against God, it implies that the act is committed ostentatiously and in bravado.

Reproacheth the Lord – Rather, reviles or blasphemes the Lord .