One day Guaire mac Éogain arrived, wishing to claim the kingdom of the Leinstermen. He harried the laypeople who were around Saint Fintán, and carried off their flocks and livestock with him. Then the widows and orphans of the lay community came to Fintán and cried before him. And Fintán, calling four men to him, said to them:
‘Go and greet Guaire and tell him, in the name of the Lord, to free the flocks that he seized. If he should heed our request, tell him that he will be king unto old age and he will not be slain, and his lineage will hold the kingdom of the Uí Chennselaig unto the day of judgement. But I know that the same man is obstinate, and he will not listen to you nor release the flocks of this people. And at that hour in which you will greet him his head will be tonsured in your presence, and you will say to him: ‘If you do not release to us the flocks of the people that you have seized, your head will not be tonsured again, but you will be slain before the hairs of your head grow, and you will be beheaded, and you will not be king’.’
These messengers left and greeted Guaire. And it happened just as Fintán said, and Guaire did not free the flocks, and he himself was slain on the fifth day.