system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] Who did the Watcher make his oath to?

The Watcher swore an oath to only observe, never to intervene. But who did he swear it to? Does the Watcher have a boss who comes by and checks to make sure that he's only watching? Uatu seems to look for loopholes in the "just watching" oath all the time, so I don't think he made that oath just on his own or else he'd be fine breaking it with no consequences.
gpt
The oath of non-interference is a defining aspect of the culture of his people.  

The Watchers are one of the first species to develop sentience after the birth of the universe, if not the first.  After developing interstellar travel, the Watchers made an attempt to accelerate the development of a younger species.  The primitive species was not ready to be responsible with the knowledge they were given, and quickly destroyed themselves with weapons of mass destruction.

This is the reason for the oath; to avoid repeating the mistake of causing harm with their good intentions.  The make the oath to themselves and their peers, and their governing council is the body that enforces it.

The Watchers still gather knowledge with the intent to share and uplift others, but now their intent is to learn as much as they can before the death of the current universe and bestow the next universe at birth with all the accumulated wisdom of its predecessor.