Exodus 31:13 (KJV)
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
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