give (one) pause
To cause one to take a moment to consider something; to cause one to hesitate. I'd love to buy a house, but the fact that I'd have to completely deplete my savings account to do it gives me pause. That statistic should give everyone pause.
give someone pause (for thought)
Fig. to cause someone to stop and think. When I see a golden sunrise, it gives me pause for thought. Witnessing an accident is likely to give all of us pause.
give pause
Cause one to hesitate, as in The high monthly installment payments gave me pause, or, as Shakespeare put it in Hamlet (3:1): "For in that sleep of death what dreams may come ... Must give us pause." [c. 1600]