Husband won't tie me up. Advice to get him comfortable

So first off I'm sorry if I put this question in the wrong room. (There's lot of sex groups on this app.)

I've been wanting to try being tied up for awhile now, but my husband doesn't want to. His sister was raped in high school so he's really big on consent and me being comfortable. Don' get me wrong I'm SO thankful for that, but does anyone have advice on how can make him understand better that I WANT it and I feel safe with him? A friend suggested I try tying him up and see if he's into it, but I don't know.