you need to know where you stand before you make your decision.

if you do not desperate for the job, just decline the request. do keep in mind, that the recruiter/employer can also say no to the candidate as well.

if you are reasonably confident that no one else can come close to your experience/skills/reputation, generally you have nothing to worry about.

to negotiate for better price, why not just say you have another offer of x amount instead with a competitor company? i think that's way better instead of playing cat and mouse with payslips. again.. hv to remember who is more desperate here.