There was a feeling of constraint in the room; no one dared to tell the king how foolish his decision was. ✬

You must put an end to this foolish behavior. ✬

It is foolish of you to build a castle in the air while forgetting to drive in pilings for its foundation. ✬

Take care not to make a foolish move. ✬

Don't risk your neck over something foolish. ✬

If you do such a foolish thing, people will laugh at you. ✬

Don't bother me with such foolish questions. ✬

I decided not to do such a foolish thing. ✬

I was foolish enough to believe it. ✬

He is foolish. ✬