The Text
The President may deprive a person, other than a person who is a citizen by birth, 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; or has shown himself by act or speech to be disloyal towards the Federal Republic of Nigeria.
Source · Constitution of the Federal Republic of Nigeria, 1999, as amended · §30