Charles Ellicott Commentary Leviticus 20:10

"And the man that committeth adultery with another man`s wife, even he that committeth adultery with his neighbor`s wife, the adulterer and the adulteress shall surely be put to death." — Leviticus 20:10 (ASV)

Shall surely be put to death. —This is the penalty for the sin forbidden in Leviticus 18:20. According to Jewish tradition, whenever the phrase “shall surely be put to death” occurs by itself, it denotes death by strangling. This death was inflicted for six crimes—upon:

1. him who committed adultery with another man’s wife;
2. him who struck his father or mother;
3. him who stole an Israelite;
4. an elder who rebelled against the decree of the senate (Deuteronomy 17:12);
5. him who acted as a false prophet;
6. and him who prophesied in the name of another god.