"Israel was holiness to Jehovah, / The firstfruits of His increase" (v. 3a). The word increase here means produce from the earth. God gained some increase from the earth as produce, and Israel was the firstfruits of this produce. As the firstfruits, Israel was valuable to God. God treasured Israel as holiness to Him, as the firstfruits of His increase from His field.
"Thus says Jehovah: / What iniquity did your fathers find in Me, / That they have gone far away from Me / And have walked after vanity / And are vain?" (v. 5). The word vanity in this verse refers to idols. Israel walked after vanity, and they themselves became vain; they worshipped idols and as a result they made themselves nothing.
Israel also forgot Jehovah, who brought them up from Egypt through the wilderness of deserts and the shadow of death and brought them into the land of the fruited field (vv. 6-7).
"The priests did not say, / Where is Jehovah? / And those who handle the law did not know Me, / And the shepherds transgressed against Me, / And the prophets prophesied by Baal / And followed after things that did not benefit them" (v. 8). The priests did not know where God was, and those who handled the law did not know God. How could they handle Jehovah's law if they did not know Him? This is impossible. Furthermore, the shepherds, the rulers, transgressed against Jehovah, and the prophets prophesied by Baal, that is, in the name of Baal, an idol. This was the situation of the people of Israel.
"Has a nation ever exchanged its gods, / Even though they are no gods? / But My people have exchanged their glory / For that which does not benefit them" (v. 11). Here the words their glory mean "their God." The people exchanged their God for idols, for that which was vain and did not benefit them.