Proverbs 4:23 (BSB)

Guard your heart with all diligence, for from it flow springs of life.

From Proverbs 4. Also in the ESV.

Commentary on Proverbs 4:23

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Proverbs 4:20-27: Solomon, having warned us not to do evil, here teaches us how to do well. It is not enough for us to shun the occasions of sin, but we must study the methods of duty. I. We must have a continual regard to the word of God and endeavour that it may be always ready to us. 1.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Proverbs 4:23: Keep thy heart with all diligence,.... The mind from vanity, the understanding from error, the will from perverseness, the conscience clear of guilt, the affections from being inordinate and set on evil objects, the thoughts from being employed on bad subjects; and the whole from falling into the hands of the enemy, or being the possession of Satan: great diligence had need be used in...
• Jamieson-Fausset-Brown (Reformed), Commentary Critical and Explanatory on the Whole Bible on Proverbs 4:23: with all diligence--or, "above," or "more than all," custody (compare Margin), all that is kept (compare Eze 38:7), because the heart is the depository of all wisdom and the source of whatever affects life and character (Mat 12:35; Mat 15:19).
• Geneva Bible Notes (Reformed), Geneva Bible Study Notes on Proverbs 4:23: Keep thy heart with all diligence; for out of it [are] the issues of life. (k) For as the heart is either pure or corrupt, so is the whole course of man's life.