“Tell the Israelites, ‘Surely you must keep My Sabbaths, for this will be a sign between Me and you for the generations to come, so that you may know that I am the LORD who sanctifies you.
Jewish Publication Society of America Version (JPS1917) - Exodus 31:13 >'Speak thou also unto the children of Israel, saying: Verily ye shall keep My sabbaths, for it is a sign between Me and you throughout your generations, that ye may know that I am the LORD who sanctify you.