What is the oldest written source in this country that mentions this right?
Jamaica
Article 22 of the 1960 Jamaica Constitution protects freedom of expression.
References:
English original text of the Constitution of 1962 820 (2011) Chapter III: Fundamental Rights and Freedoms: https://heinonline-org.proxygw.wrlc.org/HOL/Page?collection=cow&handle=hein.cow/zzjm0004&id=15&men_tab=srchresults