Malachi 3:8

The Lord proceeded to give some examples of repentance that the Israelites needed to apply. How absurd it is for human beings to rob God. To rob Him one would have to be stronger and smarter than He. Yet that is what the Israelites were doing because God was allowing it. They were thieves of the worst kind: robbers of God. They brazenly asked how they had robbed Him. They had withheld the tithes (Leviticus 27:30; Leviticus 27:32; Deuteronomy 12:5-18; Deuteronomy 14:22-29) and offerings (Numbers 18:21-32) that the Law commanded them to bring to God.

Standing beside "tithes" as it does here, "offerings" may refer to the tithe of the tithe that went to the priests (cf. Exodus 29:27-28; Leviticus 7:32; Numbers 5:9). The Levites were to receive a tenth from the people and then give a tenth of that to the priests. But the widows, orphans, and sojourners also benefited from the tithes (Deuteronomy 14:28-29), so withholding it hurt them as well. Another possibility is that Malachi was distinguishing the mandatory "tithes" from the voluntary "offerings" that the Israelites brought. Or perhaps any other offerings beside the tithes are in view. In any case, tithes and offerings constitute a merism representing all their economic responsibilities to God.

Since God owned the land and its produce in the first place (cf. Malachi 1:12-14; Leviticus 25:23), withholding tithes when He commanded the Israelites to give them amounted to robbing Him. Earlier the Lord criticized the priests for offering inferior quality sacrifices (Malachi 1:7-14), and now He criticized the people for offering an insufficient quantity of sacrifices (cf. Malachi 3:10). Failure to adequately support the priests and Levites resulted in the breakdown of priestly service (cf. Nehemiah 10:32-39; Nehemiah 13:10).