how do i tell him withiut hurting his feelings?

Ta

So my boyfriend has a bad habit of when he wants to have sex and I say no that he will continue to ask about 2 or 3 more times one right after the other. It bothers me that he keeps asking after I say no. I would understand if it was like few hours later or only a couple times a day, but it's literally I'll say no and he will ask if I'm sure about it 2 or 3 more times I guess thinking it'll change my mind. I want to tell him that it bothers me but I'm not sure how to tell him and not hurt his feelings. Does anyone have any ideas on how I could tell him with out it hurting his feelings?