Establishment of the Supreme Court of Nigeria
Section 230 · 1999 Constitution (2004 edition)
What Constitution says
(1) There shall be a Supreme Court of Nigeria. (2) The Supreme Court of Nigeria shall consist of - (a) the Chief Justice of Nigeria; and (b) such number of Justices of the Supreme Court, not exceeding twenty-one, as may be prescribed by an Act of the National Assembly.
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 101. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections