Whether it is lawful to swear by creatures?

❌ Objection 1 : It would seem that it is not lawful to swear by creatures. It is written (Mt. 5:34-36): "I say to you not to swear at all, neither by heaven . . . nor by the earth . . . nor by Jerusalem . . . nor by thy head": and Jerome, expounding these words, says: "Observe that the Saviour does not forbid swearing by God, but by heaven and earth," etc.

❌ Objection 2 : Further, punishment is not due save for a fault. Now a punishment is appointed for one who swears by creatures: for it is written (22, qu. i, can. Clericum): "If a cleric swears by creatures he must be very severely rebuked: and if he shall persist in this vicious habit we wish that he be excommunicated." Therefore it is unlawful to swear by creatures.

❌ Objection 3 : Further, an oath is an act of religion, as stated above (Article [4]). But religious worship is not due to any creature, according to Rm. 1:23,25. Therefore it is not lawful to swear by a creature.