Proverbs 21:1 (BSB)

The king’s heart is a waterway in the hand of the LORD; He directs it where He pleases.

From Proverbs 21. Also in the ESV.

Commentary on Proverbs 21:1

• Geneva Bible Notes (Reformed), Geneva Bible Study Notes on Proverbs 21:1: The king's heart [is] in the hand of the LORD, [as] the rivers of water: he turneth it wherever he will. (a) Though kings seem to have all things at commandment, they are not able to bring their own purposes to pass unless God has appointed: much less are the inferiors able.
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on Proverbs 21:1: Pro 21:1 The group, like the preceding one, now closes with a proverb of the king. A king's heart in Jahve's hand is like brooks of water; He turneth it whithersoever He will. Brook and canal (the Quinta: ὑδραγωγοί) are both called פּלג, or פּלג, Job 20:17, Arab. falaj (from פּלג, to divide, according to which Aquila, Symmachus, and Theodotion, διαρέσεις; Venet.