What is the oldest written source in this country that mentions this right?
Kingdom of the Netherlands
Freedom of association is protected under Article 8: “The right of association shall be recognized. This right may be restricted by Act of Parliament in the interest of public order” (constituteproject.org).
“Netherlands 1814 (Rev. 2008) Constitution.” Constitute. Accessed July 19, 2023. https://www.constituteproject.org/constitution/Netherlands_2008.