Upvote:3
You need to have a visa for Saudi Arabia, as it is not a connecting flight. You can take the visa as eVisa, as Czech citizens are eligible for eVisa. It is a 1 year multiple entry visa and you can possibly use it for return as well.
If you don't have a visa, then the airline will be denying you boarding, even if you are not planning to get out of airport.
Link to eVisa - https://visa.visitsaudi.com/