The first assertion of freedom of association in the 1995 constitution of the Azerbaijan Republic is mentioned under Chapter III Article 58 section I through IV.

References:

Constitution Of The Azerbaijan Republic, as amended on August 24, 2002: https://constitutionnet.org/sites/default/files/Azerbaijan%20Constitution.pdf

Blaustein, Albert P., and Gisbert H. Flanz. Constitutions of the Countries of the World; a Series of Updated Texts, Constitutional Chronologies and Annotated Bibliographies. "Azerbaijan Republic, Booklet 2, 1996" Permanent ed. Dobbs Ferry, N.Y: Oceana Publications, 1971.