From my understanding.....you are correct. The “Sabbat” or Sabbath is on Saturday.
The Scots Presbyterians (especially the "Wee Free" variety) were particularly concerned with "Sabbath-keeping" and "Sabbath-breaking". My maternal grandparents were Scots Presbyterians of the rock-ribbed variety.
George MacDonald Fraser (the "Flashman" author) once asked one of his soldiers in the Far East, a Wee Free, how he could bring himself to kill Japanese on the Sabbath. He replied that it was a work of necessity and mercy . . . .