What remains, and the ceasing of effort. In this house the second sense is honoured and never prescribed to another.
Old English ræst/rest (repose, sleep, a resting place), from Proto-Germanic rastu- (rest, a stopping place); rest has named both what remains and the ceasing of effort for as long as the word is recorded, without either sense crowding out the other.
What remains, and the ceasing of effort. The second sense is the one honoured here and never prescribed to anyone else — the root allows both readings, and only one of them is ever a rule for someone else to follow.