What is "day of rest"

Usage examples of "day of rest".

Now, Waterhouse knows what that means, having spent many a Sabbath on Qwghlm, cringing and blushing under the glares of the locals, who were outraged that he appeared to be running the huffduff equipment on the day of rest.

My uncle here paid Hans his usual rix-dollars, and it was decided that the next day should be a day of rest.