Genesis 31:28הִסְכַּלְתָּ
But you did not even let me kiss my grandchildren and my daughters goodbye. Now you have done a foolish thing.
1 Samuel 13:13נִסְכָּלְתָּ
“You have acted foolishly,” Samuel declared. “You have not kept the command that the LORD your God gave you; if you had, the LORD would have established your kingdom over Israel for all time.
2 Samuel 24:10נִסְכַּלְתִּי
After David had numbered the troops, his conscience was stricken and he said to the LORD, “I have sinned greatly in what I have done. Now, O LORD, I beg You to take away the iniquity of Your servant, for I have acted very foolishly.”
1 Chronicles 21:8נִסְכַּלְתִּי
Then David said to God, “I have sinned greatly because I have done this thing. Now I beg You to take away the iniquity of Your servant, for I have acted very foolishly.”
2 Chronicles 16:9נִסְכַּלְתָּ
For the eyes of the LORD roam to and fro over all the earth, to show Himself strong on behalf of those whose hearts are fully devoted to Him. You have acted foolishly in this matter. From now on, therefore, you will be at war.”
Isaiah 44:25יְשַׂכֵּל
who foils the signs of false prophets and makes fools of diviners, who confounds the wise and turns their knowledge into nonsense,

Brown-Driver-Briggs

[סָכַל] vb. be foolish or a fool, usu. in moral or spiritual sense

Piel make foolish, turn into foolishness

Niph. act or do foolishly

Hiph. do foolishly, play the fool

Sources: Brown-Driver-Briggs (1906, public domain) from the Open Scriptures Hebrew Lexicon (CC BY 4.0), glosses from STEPBible TBESH (CC BY 4.0); STEPBible TAHOT (Hebrew Bible, Leningrad Codex, CC BY 4.0); the Berean Standard Bible (public domain). Reformatted by Word Study, wording unchanged. All sources and licenses.