The Text
The following persons are citizens of Nigeria by birth: every person born in Nigeria before the date of independence, either of whose parents or any of whose grandparents belongs or belonged to a community indigenous to Nigeria; every person born in Nigeria after the date of independence either of whose parents or any of whose grandparents is a citizen of Nigeria; and every person born outside Nigeria either of whose parents is a citizen of Nigeria.
Source · Constitution of the Federal Republic of Nigeria, 1999, as amended · §25