Exodus 31:13 in the World English Bible
“Speak also to the children of Israel, saying, ‘Most certainly you shall keep my Sabbaths; for it is a sign between me and you throughout your generations, that you may know that I am the LORD who sanctifies you.
Context
12 And the LORD spake unto Moses, saying,
13 Speak thou also unto the children of Israel, saying, Verily my sabbaths ye shall keep: for it is a sign between me and you throughout your generations; that ye may know that I am the LORD that doth sanctify you.
14 Ye shall keep the sabbath therefore; for it is holy unto you: every one that defileth it shall surely be put to death: for whosoever doeth any work therein, that soul shall be cut off from among his people.