What is the oldest written source in this country that mentions this right?

Bhutan

In The Kingdom of Bhutan all Bhutanese citizens are granted the right to free speech and expression under article 7 of the 2008 constitution. This does however only apply to those citizens of Bhutan.

References:

Bhutan 2008 Constitution: https://www.constituteproject.org/constitution/Bhutan_2008

Freedom of Expression · Country sources (all rights) · Last edited 2024-03-08 · Edit on GitHub