Adam Clarke on Malachi 3:16

They that feared the Lord - There were a few godly in the land, who, hearing the language and seeing the profligacy of the rebels above, concluded that some signal mark of God's vengeance must fall upon them; they, therefore, as the corruption increased, cleaved the closer to their Maker. There are three characteristics given of this people, viz.: -

1. They feared the Lord. They had that reverence for Jehovah that caused them to depart from evil, and to keep his ordinances.

2. They spake often one to another. They kept up the communion of saints. By mutual exhortation they strengthened each other's hands in the Lord.

3. They thought on his name. His name was sacred to them; it was a fruitful source of profound and edifying meditation. The name of God is God himself in the plenitude of his power, omniscience, justice, goodness, mercy, and truth. What a source for thinking and contemplation! See how God treats such persons: The Lord hearkened to their conversation, heard the meditations of their hearts; and so approved of the whole that a book of remembrance was written before the Lord - all their names were carefully registered in heaven. Here is an allusion to records kept by kings, Est 6:1, of such as had performed signal services, and who should be the first to be rewarded.