Deprivation of citizenship
Section 30(1) · 1999 Constitution (2004 edition)
What Constitution says
(1) The President may deprive a person, other than a person who is a citizen of Nigeria by birth or by registration, of his citizenship, if he is satisfied that such a person has, within a period of seven years after becoming naturalised, been sentenced to imprisonment for a term of not less than three years.
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 33. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections