If a friend asks you to lie for them, they’re asking you to share the consequences too.

A request like that is bigger than it sounds when it is made. Agreeing puts your name inside their story, so if it comes apart you are a participant rather than a bystander, and the person asked usually has the most to lose. Friends do not always realise they are asking for that.

You can say you will not lie and still be on their side, which is a real sentence you are allowed to use. Offer the help you can actually give instead: going with them, being there afterwards, saying nothing at all. If they only want you for the lie, that is worth knowing now.