Sancus

In Roman mythology, Sancus was the god of loyalty, honesty and oaths. His cult is one of the most ancient of Romans, probably derived from Etruscan or Oscian[?] influences.

He was also the god who protected the loyalty in commerce, and the contracts in particular. Some forms of swearings were used in his name and honour at the moment of the subscription of contracts and other important civil acts. Some words (like sanction - for the case of disrespect of pacts) have their etymology in the name of this god.

There was a temple to him on the Quirinale Hill, under the name Semo Sancus Dius Fidus.