Mark 6:26

The king was sorry, i.e., he pretended to be so, say SS. Hilary and Jerome. For he really wished John to be killed, as Matthew says. Wherefore the Gloss on the fourteenth of S. Matthew says, "Herod's sorrow was like Pilate's repentance" And the Interlinear, "The dissembler showed sorrow in his face, but was glad in his heart."

But more simply. S. Chrysostom and Euthymius think that Herod was really sorry is the meaning of SS. Matthew and Mark. For though he wished John to die, yet he was sorry for his cruel and shameful death, that he should have killed so great a prophet for the gratification of a dancing girl.

For his oath's sake. Herod made a pretext of his oath; for he knew that in such a case, that is, at such an iniquitous and sacrilegious a request of the girl, it was not binding. However, he thought it a king's part not to retract it before the nobles, according to the saying, The word of the king is the king. Thus this worldling acted. Whence S. Augustine says, "A girl dances, and a mother rages, and there is rash swearing in the midst of the luxurious feast, and an impious fulfilment of what was sworn." For, as S. Isidore says, faith ought to be broken in wicked promises; that is, an impious promise which is fulfilled by a crime.