It's on NIST SP 800-63B 5.1.1.2[1]:

> Verifiers SHOULD NOT require memorized secrets to be changed arbitrarily (e.g., periodically). However, verifiers SHALL force a change if there is evidence of compromise of the authenticator.

[1]: https://pages.nist.gov/800-63-3/sp800-63b.html#memsecretver