4x12 - The Adventures of Robin Hood

The Deputy Sheriff suspects Friar Tuck of being in league with the outlaws, so he tries to turn the Archbishop against him. He hatches a plot for the Friar to take an oath in front of the Archbishop to prove that he doesn't consort with the outlaws. Tuck must takes an oath in front of the Archbishop not to reveal the identity or the location of the Sheriff's latest prisoner — an envoy of King Richard about to be hung. Tuck cannot break his oath and tell Robin to save the man, so he uses his cunning instead.