Malachi 1:1 introduces the book as a revelation, Yahweh's word to Israel by Malachi. Malachi is built from a series of disputes: God speaks, the people push back with a question, and God answers. The first dispute begins with love. I have loved you, says Yahweh. The people reply, how have you loved us? God points to how he chose Jacob rather than Esau and protected his people.
The second dispute targets the priests. God says, a son honors his father, and a servant his master. If I am a father, then where is my honor? The priests ask, how have we despised your name? God answers that they offer polluted bread and blind, lame, and sick animals. He says, present it now to your governor! Will he be pleased with you? God would rather someone shut the temple doors than continue such empty worship.
Against this careless worship, God sets a vision of his greatness. God says, from the rising of the sun even to its going down, my name is great among the nations, and in every place incense will be offered to my name. The priests sniffed at their duties and said, what a weariness it is! But God declares, I am a great King, says Yahweh of Armies, and my name is awesome among the nations. Worship that costs nothing honors nothing.