The chain will be slightly wider for 8sp, and everyone will tell you that you need a 9sp chain on 9sp cassette. Theoretically speaking you *might* get away with tolerable shifting, but at the risk of accelerated wear of both chain & cassette. See if anyone responds who’s tried such a combo for in practice…
Personally I’d try to sell / exchange them for 9sp chains (have seen them for £9ish) and not risk poor shifting / cassette wear which could ultimately cost more.