Bede's Ecclesiastical History of England, ed. by A.M. Sellar, , at sacred-texts.com
AT their first coming into Frisland, as soon as Wilbrord found that he had leave given him by the prince to preach there, he made haste to go to Rome, where Pope Sergius then presided over the Apostolic see, that he might undertake the desired work of preaching the Gospel to the nations, with his licence and blessing; and hoping to receive of him some relics of the blessed Apostles and martyrs of Christ; to the end, that when he destroyed the idols, and erected churches in the nation to which he preached, he might have the relics of saints at hand to put into them, and having deposited them there, might accordingly dedicate each of those places to the honour of the saint whose relics they were. He desired also there to learn or to receive many other things needful for so great a work. Having obtained his desire in all these matters, he returned to preach.
At which time, the brothers who were in Frisland, attending on the ministry of the Word, chose out of their own number a man of sober life, and meek of heart, called Suidbert, to be ordained bishop for them. He, being sent into Britain, was consecrated, at their request, by the most reverend Bishop Wilfrid, who, having been driven out of his country, chanced then to be living in banishment among the Mercians; for Kent had no bishop at that time, Theodore being dead, and Bertwald, his successor, who had gone beyond the sea to be ordained, having not yet returned to his episcopal see.
The said Suidbert, being made bishop, returned from Britain, and not long after departed to the Boructuari; and by his preaching brought many of them into the way of truth; but the Boructuari being not long after subdued by the Old Saxons, those who had received the Word were dispersed abroad; and the bishop himself with certain others went to Pippin, who, at the request of his wife, Blithryda, gave him a place of abode in a certain island on the Rhine, called in their tongue, Inlitore; there he built a monastery, which his successors still possess, and for a time dwelt in it, leading a most continent life, and there ended his days.
When they who had gone thither had spent some years teaching in Frisland, Pippin, with the consent of them all, sent the venerable Wilbrord to Rome, where Sergius was still pope, desiring that he might be consecrated archbishop over the nation of the Frisians; which was accordingly done, as he had made request, in the year of our Lord 696. He was consecrated in the church of the Holy Martyr Cecilia, on her festival; and the said pope gave him the name of Clement, and forthwith sent him back to his bishopric, to wit, fourteen days after his arrival in the city.
Pippin gave him a place for his episcopal see, in his famous fort, which in the ancient language of those people is called Wiltaburg, that is, the town of the Wilts; but, in the Gallic tongue, Trajectum. The most reverend prelate having built a church there, and preaching the Word of faith far and near, drew many from their errors, and built many churches and not a few monasteries. For not long after he himself constituted other bishops in those parts from the number of the brethren that either came with him or after him to preach there; of whom some are now fallen asleep in the Lord; but Wilbrord himself, surnamed Clement, is still living, venerable for his great age, having been thirty-six years a bishop, and now, after manifold conflicts of the heavenly warfare, he longs with all his heart for the recompense of the reward in Heaven.’