What's the best way to give a secret gift?

I have a friend who is going through a rough time this year… He was injured at work earlier this year and ended up being on workers comp for 6ish months… and has like 6 kids and a stay at home wife

The gift is going to be money, so how can I do this so he gets it but doesn’t know who it’s from….?
because of the amount, I don’t want to leave it out somewhere for him to find….or mail it…