There is no need whatsoever to whip a child of 4. It is wrong to whip a child when he is naughty. Children who are bright and energetic will try and do new things all the time. Some of their actions may disturb your routine. But they are NOT to be treated with mindless physical punishment.
By staring at you in the face, your son is saying that he is not afraid of you. You will have to use patience and affectionate reasoning with your child. You should not whip him. You should win him over with reasonable rules and actions. If the children attend a preschool or play centre, do consult the teachers also about dealing with your children.