Ministers of the Federal Government
Section 147(4) · 1999 Constitution (2004 edition)
What Constitution says
(4) Where a member of the National Assembly or of a House of Assembly is appointed as Minister of the Government of the Federation, he shall be deemed to have resigned his membership of the National Assembly or of the House of Assembly on his taking the oath of office as Minister.
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 74. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections