Charles Ellicott Commentary Jeremiah 2:3

"Israel [was] holiness unto Jehovah, the first-fruits of his increase: all that devour him shall be held guilty; evil shall come upon them, saith Jehovah." — Jeremiah 2:3 (ASV)

Holiness unto the Lord. —The thought was that expressed in the inscription on the gold plate worn on the high priest’s forehead (Exodus 28:36), and in the term “holy thing” (Leviticus 22:10; Matthew 7:6), applied to the consecrated gifts which were the portion of the priests. The prophet was taught that Israel, as a nation, had a priestly character, and was consecrated to the Lord as the “firstfruits” of the great harvest of the world. Compare the use of the same figure in James 1:18; Romans 11:16.

All that devour him shall offend.—The imagery of the firstfruits is continued. The Hebrew for the word “offend” is used for transgressions against the ceremonial law in Leviticus 5:5; Leviticus 5:19; Numbers 5:7. Here, however, it is probably better rendered, shall be condemned, or shall be made to suffer, as in Psalms 34:21-22, where the Authorized Version has shall be desolate. Those who devour Israel—the enemies and invaders, the tyrants and oppressors—are guilty as of a sacrilege that will not remain unpunished.