C.H. Spurgeons's The Treasury of David
Verse 4. A froward heart shall depart from me. He refers both to himself and to those round about him; he would neither be crooked in heart himself, nor employ persons of evil character in his house; if he found such in his court he would chase them away. He who begins with his own heart begins at the fountain head, and is not likely to tolerate evil compamons. We cannot turn out of our family all whose hearts are evil, but we can keep them out of our confidence, and let them see that we do not approve of their ways.
I will not know a wicked person. He shall not be my intimate, my bosom friend. I must know him as a man or I could not discern his character, but if I know him to be wicked, I will not know him any further, and with his evil I will have no communion. "To know" in Scripture means more than mere perception, it includes fellowship, and in that sense it is here used. Princes must disown those who disown righteousness; if they know the wicked they will soon be known as wicked themselves.
EXPLANATORY NOTES AND QUAINT SAYINGS
Verse 4. A froward heart. The original sense of fq[ is torsit, contorsit, to twist together, and denotes, when applied to men, persons of a perverse, subtle disposition, that can twist and twine themselves into all manner of shapes, and who have no truth and honour to be depended on. --Samuel Chandler.
Verse 4. A froward heart. By which I understand "from-wardness" -- giving way to sudden impulses of anger, or quick conception, and casting it forth in words or deeds of impetuous violence. --Thomas Chalmers.
HINTS FOR PASTORS AND LAYPERSONS
Verse 4. -- The need of extreme care in the choice of our intimates.