"Sabbath is not dependent upon our readiness to stop. We do not stop when we are finished. We do not stop when we complete our phone calls, finish our project, get through this stack of messages, or get out this report. We stop because it is time to stop. Sabbath requires surrender. If we only stop when we are finished with all our work, we will never stop—because our work is never completely done."
See also "Ancient Practices - Sabbath."