Election: two or more presidential candidates
Section 134(1) · 1999 Constitution (2004 edition)
What Constitution says
(1) A candidate for an election to the office of President shall be deemed to have be been duly elected, where, there being only two candidates for the election - (a) he has the majority of votes cast at the election; and (b) he has not less than one-quarter of the votes cast at the election in each of at least two- thirds of all the States in the Federation and the Federal Capital Territory, Abuja.
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 68. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections