What is the recommended time before a reset password link expires?

I'm working on a financially leaning site and was curious — is there a standard amount of time to wait before expiring a reset password link once a user has forgotten his/hers and requested to reset it?

On the other hand, if there is no "standard" as such, how might a UX practitioner go about figuring out what would be a sensible and acceptable period for their use case?