scolding

Q: I was at a restaurant with my brother and two boys were staring at us. While leaving, I went to them and told them to feel ashamed as they are staring like this. Did I commit a sin? What should I have done? How can I ask for forgiveness from Allah?

Q: One mother has two daughters. The mother always likes the elder daughter. The mother always uses some bad words and scolds the younger daughter. If the mother scolds the daughter like this, will the daughters life be spoiled? How will the scolding of a mother affect her daughters life even though the daughter did not make any mistake.