Matthew Henry's Complete Bible Commentary

Verse 3

Note, 1. The hearts of the children of men are subject, not only to God’s view, but to his judgment: As the fining-pot is for silver, both to prove it and to improve it so the Lord tries the hearts; he searches whether they are standard or no, and those that are he refines and makes purer, Jeremiah 17:10. God tries the heart by affliction (Psalms 66:10, 66:11), and often chooses his people in that furnace (Isaiah 48:10) and makes them choice. 2. It is God only that tries the hearts. Men may try their silver and gold with the fining-pot and the furnace, but they have no such way of trying one another’s hearts; God only does that, who is both the searcher and the sovereign of the heart. MHBCC 646.3