go easy on (someone or something)
1. To be lenient with someone, especially after they've done something that could justify a punishment or scolding. Go easy on your little brother, will you? He didn't mean to break the window. I only lost by six points, but I think he was going easy on me since he's so much better.
2. To use only a small amount of something. Hey, go easy on the ketchup—there's not much left.