St. Adamnan (Eunan), the biographer of St. Columba, tells many interesting incidents in the life of St. Baithen, but the mere fact of being the immediate successor of St. Columba, by the express wish of that apostle, is almost sufficient to attest his worth. The “Martyrology of Donegal” records the two following anecdotes. When St. Baithen partook of food, before each morsel in invariably recited “Deus in adjutorium meum intende”. Also, “when he worked in the fields, gathering in the corn along with the monks, he used to hold up one hand towards Heaven, beseeching God, while with the other hand he gathered the corn”. St. Baithen of Iona is generally known as Baithen Mor, to distinguish him from eight other saints of the same name — the affix mor meaning “the Great”. He wrote a life of his master, and some Irish poems, which are now lost, but which were seen by St. Adamnan. He only ruled Iona three years, as his death took place in the year 600, though the “Annals of Ulster” give the date as 598. Perhaps the true year may be 599. His feast is celebrated on October 6th. Some writers assert that St. Baithen of Iona is the patron of Ennisboyne, County Wicklow, but this is owing to a confusion with St. Baoithin, or Baithin mac Findech, whose feast is commemorated on 22 May. Another St. Baoithin, son of Cuana, whose feast is on 19 February, is patron of Tibohin, in Elphin.
An Irish monk, specially selected by St. Columba as one of the band of missionaries who set sail for Britain in 563. Born in 536, the son of Brenaron, he was an ardent disciple of St. Columba, and was appointed Abbot of Tiree Island, a monastery founded by St. Comgall of Bangor. St. Adamnan, in recording the death of St. Columba, tells us that the dying words of the Apostle of Iona, as he was transcribing the fifty-third Psalm, were: “I must stop here, let Baithen write what follows”. Baithen had been looked on as the most likely successor of St. Columba, and so it happened that on the death of that great apostle, in 596, the monks unanimously confirmed the choice of their founder. St. Baithen was in high esteem as a wise counsellor, and his advice was sought by many Irish saints, including St. Fintan Munnu of Taghmon.
From Catholic Encyclopedia