Exodus 31:14 KJV
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.
Exodus 31:14, King James Version
In context
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.
15 Six days may work be done; but in the seventh is the sabbath of rest, holy to the Lord: whosoever doeth any work in the sabbath day, he shall surely be put to death.