Well, circumcision was a ”seal” (covenant) for those under the old covenant.
The Sabbath was the "sign" of the Sinai covenant.
Exo 31:13 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.
Exo 31:14 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.
Exo 31:15 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.
Circumcision was the "sign" or "token" of the Abrahamic covenant.
Gen_17:11 And ye shall circumcise the flesh of your foreskin; and
it shall be a token of the covenant betwixt me and you.
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