N.D. Cent. Code § 6-08-22
Nothing in any law in this state may in any manner whatsoever affect the validity of, or render void or voidable, the payment, certification, or acceptance of a check or other negotiable instrument or any other transaction by a bank or trust company in this state because done or performed during any other than regular banking hours, provided, further, that nothing herein may be construed to compel any bank or trust company in this state, which by law or custom is entitled to close at twelve noon on any Saturday, or for the whole or any part of any legal holiday, to keep open for the transaction of business, or to perform any of the acts or transactions aforesaid on any Saturday after such hour, or on any legal holiday, except at its own option.
N.D.C.C. § 6-08-22