C. F. Keil and Franz Delitzsch on Proverbs 19:21

Pro 19:21 21 Many are the thoughts in a man’s heart;      But Jahve’s counsel, that stands.

In תּקוּם lies, as at Isa 40:8, both: that the counsel of God (His plan of the world and of salvation) is accomplished and comes into actual fact, and that it continues. This counsel is the true reality elevated above the checkered manifoldness of human purposes, aims, and subjectivities, which penetrates and works itself out in history. The thoughts of a man thus gain unity, substance, endurance, only in so far as he subjects himself to this counsel, and makes his thoughts and actions conformable and subordinate to this counsel.