Citizenship by registration
Section 26(2) · 1999 Constitution (2004 edition)
What Constitution says
(2) the provisions of this section shall apply to- (a) any woman who is or has been married to a citizen of Nigeria; or (b) every person of full age and capacity born outside Nigeria any of whose grandparents is a citizen of Nigeria.
This is the 1999 Constitution as published in 2004. Later amendments aren't included yet, so a section may have changed since.
Original source
Official Gazette · CFRN 1999 official PDF · printed page 31. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections