hold still
To remain motionless or stop moving. Often used as an imperative. Hold still so I can look at your cut. If you don't hold still and quit squirming, I won't be able to cut your hair!
hold still
(for someone or something) and keep still (for someone or something); stand still (for someone or something) to remain motionless for someone or something. Hold still for the doctor and the shot won't hurt. Please keep still for the doctor.