Article 2 of the Constitution of the Fifth French Republic
Article 2 of the Constitution of the French Fifth Republic establishes the official language, national symbols, motto, and principle of government of the French Republic, effective since the establishment of the Fifth Republic on 5 October 1958. == Text == The language of the Republic is French.
Source: Wikipedia — Article 2 of the Constitution of the Fifth French Republic (CC BY-SA 4.0)