Trust in the LORD with all thine heart; and lean not unto thine own understanding.
Trust in the Lord with all thine heart; and lean not unto thine own understanding - which latter cannot preserve thee. He guards against his recommendation of "good understanding" (a different Hebrew term from that here, which is binath) in Proverbs 3:4 being perverted into a ground for self-reliance. Begin with the Lord in the pursuit whether of knowledge or wealth. While you use all exertions of head and hands, regard God as all-sufficient for thee, as to obtaining every good and averting every evil. "Rest in Him," assured of His gracious will and power to save and help thee in all exigencies (Psalms 37:7). Casting every burden on Him (Psalms 55:22; 1 Peter 5:7). "Not of double heart" (1 Chronicles 12:33; James 1:8). Not thrown into doubt or consternation by external circumstances, so as to lose fearless trust in God. To "lean" upon one's own understanding is to lean on a broken reed, which will pierce the hand, as Egypt proved when Israel leant on it (2 Kings 18:21; Ezekiel 29:7; 2 Chronicles 14:11. "We rest on thee;" Isaiah 10:20. "The remnant of Israel shall stay upon the Lord, the Holy One of Israel, in truth"). Man's own understanding is not to be trusted in, as being weakened and corrupted, at the same time that it is puffed up with pride, ever since the fall. Therefore it is written, Isaiah 47:10, "Thy wisdom and thy knowledge it hath perverted thee;" Jeremiah 10:23, "The way of man is not in himself."