“The king’s heart is in the hand of the LORD, as the rivers of water: He turneth it whithersoever He will.
Every way of a man is right in his own eyes: but the LORD pondereth the hearts.
To do justice and judgment is more acceptable to the LORD than sacrifice.
An high look, and a proud heart, and the plowing of the wicked, is sin.
The thoughts of the diligent tend only to plenteousness; but of every one that is hasty only to want.
The getting of treasures by a lying tongue is a vanity tossed to and fro of them that seek death.
The robbery of the wicked shall destroy them; because they refuse to do judgment.
The way of man is froward and strange: but as for the pure, his work is right.” Proverbs 21:1-8 (KJV)

It is a staple of life to know that God can take the heart of a king; any ruler in the world; and turn it the direction He chooses. Even when the king is evil, from an evil empire or kingdom, God uses kings to fulfill His will and purposes. That the world may know that He is the LORD.

Verses 1 – 4 – Streams of water are often changed in their courses due flood waters. In the early 1800’s [1811-1812] the Mississippi River flowed backwards for a period of 10-24 hours filling, forming the Reelfoot lake. Even streams as massive as the Mississippi can be changed by the hand of God; so too can a king’s heart.

Examples of king’s hearts being changed can be seen in Pharoah, Nebuchadnezzar, Belshazzar, Ahaseurus, Darius, Cyrus (Exodus 12:31; Daniel 4; 5; 6; 10; Ezra 1, 4; Esther 9-10).

The Lord looks on and knows the hearts of mankind. Even Jesus is said to have known what was on the hearts of some people who wanted to force Him to be king (John 2:23-25; 6:14-15).

The “High look” and the “Proud heart” go like peas in their pod. The plowing of the wicked, leads to the sowing of sin. “Whatsoever a man soweth, that shall he also reap” (Galations 6:7)

Verses 5 – 8 – There is contrast in v. 5 between the diligent and the hasty. There is reward for diligence; while there is waste and want to the hasty.
“The getting of treasures by a lying tongue,…. By telling lies in trade; by bearing false witness in a court of judicature; or by preaching false doctrines in the church of God:
is a vanity tossed to and fro of them that seek death: such treasures, though ever so great, are like any light thing, smoke or vapour, straw, stubble, chaff, or a feather, tossed about the wind; which is expressive of the instability uncertainty of riches ill gotten; they do not last long, but are taken away and carried off by one providence or another; and they are likewise harmful and pernicious; they issue in death: and those that seek after them, and obtain them in a bad way, are said to “seek death”: not intentionally, but eventually; this they certainly find, if grace prevent not; see Pro_8:36. Jarchi reads it, they are the “snares of death” to him; and so the Septuagint version.” From John Gill Commentary, e-Sword

MacArthur Study Bible note “21:5-7  These verses address the evils of ill-gotten gain. They show three major defects in the way this gain is acquired: 1) hastily (v. 5; cf. 19:2;28:20); 2) deceitfully (v. 5 cf. 13:11); and 3) violently (v. 7; cf. 12:6).

Verse 7 – NKJV “The violence of the wicked will destroy them, Because they refuse to do justice.”
ESV “The violence of the wicked will sweep them away, because they refuse to do what is just.”

Verse 8 – People without God, and walking in His paths live lives which are perverse, crooked, criminal, and guilt riden lives. The path of those who walk with God, are pure through the purity of Christ Jesus and do right through Him. Since God can change the hearts of kings, princes, and presidents just think what He can do in your heart and life when we yield to His will.