Nigeria

(1) Subject to the provisions of this Constitution, the executive powers of the Federation:
(a) shall be vested in the President and may, subject as aforesaid and to the provisions of any law made by the National Assembly, be exercised by him either directly or through the Vice-President and Ministers of the Government of the Federation or officers in the public service of the Federation;
… (Sec. 5)

…
(3) The composition of the Government of the Federation or any of its agencies and the conduct of its affairs shall be carried out in such a manner as to reflect the federal character of Nigeria and the need to promote national unity, and also to command national loyalty, thereby ensuring that there shall be no predominance of persons from a few States or from a few ethnic or other sectional groups in that Government or in any of its agencies.
… (Sec. 14)

(1) There shall be such offices of Ministers of the Government of the Federation as may be established by the President.
(2) Any appointment to the office of Minister of the Government of the Federation shall, if the nomination of any person to such office is confirmed by the Senate, be made by the President.
Provided that no Ministerial nominee shall be confirmed by the Senate unless evidence of declaration of assets and liabilities of the nominee as prescribed in this Constitution is presented.
(3) Any appointment under subsection (2) of this section by the President shall be in conformity with the provisions of section 14(3) of this Constitution:
Provided that in giving effect to the provisions aforesaid the President shall appoint at least one Minister from each State, who shall be an indigene of such State.
(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.
(5) No person shall be appointed as a Minister of the Government of the Federation unless he is qualified for election as a member of the House of Representatives.
… (Sec. 147)