Here is the incident from in the 12th C. Life of St. Cadog* (English Translation), we have:

One day, when saint Cadog sat in his chair, teaching the people, fifty of the soldiers of a certain regulus, to wit, Paul, surnamed Penychen, who with hawks were catching birds, came to him to take food from him willy-nilly, to whom he, as it is said, ordered fifty wheaten loaves to be given, and a measure, that is, a cask full of beer, also a fat grazing sow. All these being taken and carried off by them to the midst of the plain, which is called Medgart, not far from the fort, and, being there deposited, they lay down about the measure of beer in order in the manner of a circle sur­rounding it, and the pig being cut in pieces to be roasted, they carefully prepared dinner. For there was a certain captain of that guard, Illtud by name, who was absent when they committed this crime, and before whose arrival they by no means presumed to dine. Therefore, while they were waiting for him, and abstaining on that account from the prepared food, behold, suddenly, while Illtud was coming up, but before he had alighted from his horse, the ground unexpectedly breaking under them, in the twinkling of an eye they are submerged in the depth of an abyss, according to that word of David, ‘The earth opened, and swallowed up Dathan, and covered the congregation of Abiram.’ But the food and the measure of beer, which I have referred to above, being conveyed by a divine token to a certain mound, remained inviolate and untouched. Inasmuch as the aforesaid Illtud saw these things with his own eyes, with speedy course falling down at the feet of the blessed Cadog, he told how divine vengeance had destroyed his comrades, to wit, the retinue of the aforesaid regulus, for the injury done to him by them. Indeed, that same lord or officer besought the man of God with earnest entreaties by the name of the divine majesty, that he would bestow on him the monk’s habit, and that he would ennoble him with the marks of divine service, the shaving off of hair and beard. Then he assenting to his prayers, that same officer, earthly warfare being abandoned, and secular weapons being completely renounced, having been made a monk, obeying the teachings of his preceptor with all his might, yielded himself up to the holy works of God. Wherefore it is said,

The ground swallowed them,	||	never to return to earth;
Illtud believed	||	when he had seen such acts;
He who had been a soldier,	||	subduing many strongholds,
Changed his warfare,	||	seizing the highest crown;
Becoming a monk,	||	he profited in diverse ways.

So the man of the Lord sent over some youths to bring back the mentioned food and drink, and therewith satisfied as many needy ones as there had been robbers to whom it had formerly been thanklessly surrendered.

There is a similar tale involving another king in the same life - in this tale a chief, Sawyl Benuchel, takes food and drink from the monks with his men. The monks prayed for retribution, but Cadog recommends they wait until they are asleep with booze and then shave off half their beard and hair. This suggestion, which to modern eyes looks like the work of students but was probably more shaming, was followed by the more horrific suggestion that they shave off their horses' lips and ears - which they did, being men of god. Cadog then recommends a readiness for battle, and leads the monks out to fight armed only with prayers and chants. As Sawyl and his men prepare to attack, the ground opens and swallows them (the Life notes that the ditch is still extant and refuses to be filled). The monks return singing ‘Te Deum laudamus’, pretty pleased with themselves. Cadog then uses the triumph to dictate that as they have been so wise, 12 of them should judge in the legal system of the country, with their deputies being 12 unordained clerics, and in their absence, 12 small boys and girls with unmarried women.