what can I say

Yesterday afternoon while I was in our back yard my son went out to play with his bicycle. When I was about to go inside the house, he asked me if he could play in the sand box, I said no! But he still asking me many times that please mama; I want to play in the sand. I said no again and told him to get inside. He still insisting and never listen to what I said. Until he said “it makes me happy if you let me play in the sand for a few minutes” what can I say, he is my son and it makes him happy if I let him play in the sand, so I opened the box and let him in. he was playing their for a few minutes until he got tired and went inside.