Charles Ellicott Commentary Leviticus 5:15

"If any one commit a trespass, and sin unwittingly, in the holy things of Jehovah; then he shall bring his trespass-offering unto Jehovah, a ram without blemish out of the flock, according to thy estimation in silver by shekels, after the shekel of the sanctuary, for a trespass-offering:" — Leviticus 5:15 (ASV)

If a soul commit a trespass. —The word used here for trespass is not the same as the one translated that way in Leviticus 5:19, and from which the noun translated in this very chapter as trespass offering (Leviticus 5:6–7; Leviticus 5:15–16; Leviticus 5:19) is derived. It literally means to cover, then to act secretly, or to be unfaithful, especially in matters of a sacred covenant made either with God (Leviticus 26:40; Numbers 31:16; Deuteronomy 32:51, and others) or between husband and wife (Numbers 5:12; Numbers 5:27).

And sin through ignorance. —This means if, at the time of its commission, he did not know that it was a transgression .

In the holy things of the Lord. —That is, inadvertently keeping back the things that belong to the sanctuary and to the service of the Lord; for instance, the tithes, the firstfruits, or not consecrating or redeeming his firstborn (Exodus 28:38; Numbers 5:6–8).

A ram without blemish. —For committing any of these transgressions presumptuously, the transgressor incurred the punishment of excision (Numbers 15:30; Hebrews 10:28); but when they were committed unknowingly, he was to bring a ram as a sacrifice. According to the rules that were in place during the Second Temple period, it had to be over thirty-one days old and in the second year of its age. It was more valuable than a female sheep. The sacrifice for a trespass in holy things, even if committed in ignorance, was therefore more costly than for the sin of ignorance mentioned in Leviticus 5:6.

With thy estimation by shekels of silver. —That is, according to the valuation of Moses (to whom this was primarily addressed), the ram was to be grown enough to be worth several, or at least two, shekels. The act of valuing was transferred by Moses to the officiating priests (Leviticus 27:12; Numbers 18:16). For the shekels of the sanctuary, see Exodus 30:13.