Bede's Ecclesiastical History of England, ed. by A.M. Sellar, , at sacred-texts.com
In the third year of the reign of Aldfrid, Caedwalla, king of the West Saxons, having most vigorously governed his nation for two years, quitted his crown for the sake of the Lord and an everlasting kingdom, and went to Rome, being desirous to obtain the peculiar honour of being cleansed in the baptismal font at the threshold of the blessed Apostles, for he had learned that in Baptism alone the entrance into the heavenly life is opened to mankind; and he hoped at the same time, that being made clean by Baptism, he should soon be freed from the bonds of the flesh and pass to the eternal joys of Heaven; both which things, by the help of the Lord, came to pass according as he had conceived in his mind. For coming to Rome, at the time that Sergius was pope, he was baptized on the Holy Saturday before Easter Day, in the year of our Lord 689, and being still in his white garments, he fell sick, and was set free from the bonds of the flesh on the 20th of April, and obtained an entrance into the kingdom of the blessed in Heaven. At his baptism, the aforesaid pope had given him the name of Peter, to the end, that he might be also united in name to the most blessed chief of the Apostles, to whose most holy body his pious love had led him from the utmost bounds of the earth. He was likewise buried in his church, and by the pope’s command an epitaph was written on his tomb, wherein the memory of his devotion might be preserved for ever, and the readers or hearers thereof might be stirred up to give themselves to religion by the example of what he had done.
The epitaph was this :— "High estate, wealth, offspring, a mighty kingdom, triumphs, spoils, chieftains, strongholds, the camp, a home; whatsoever the valour of his sires, whatsoever himself had won, Caedwal, mighty in war, left for the love of God, that, a pilgrim king, he might behold, Peter and Peter’s seat, receive at his font pure waters of life, and in bright draughts drink of the shining radiance whence a quickening glory streams through all the world. And even as he gained with eager soul the prize of the new life, he laid aside barbaric rage, and, changed in heart, he changed his name with joy. Sergius the Pope bade him be called Peter, himself his father, when he rose born anew from the font, and the grace of Christ, cleansing him, bore him forthwith clothed in white raiment to the heights of Heaven. wondrous faith of the king, but greatest of all the mercy of Christ, into whose counsels none may enter! For he came in safety from the ends of the earth, even from Britain, through many a nation, over many a sea, by many a path, and saw the city of Romulus and looked upon Peter’s sanctuary revered, bearing mystic gifts. He shall walk in white among the sheep of Christ in fellowship with them; for his body is in the tomb, but his soul on high. Thou mightest deem he did but change an earthly for a heavenly sceptre, whom thou seest attain to the kingdom of Christ."
"Here was buried Caedwalla, called also Peter, king of the Saxons, on the twentieth day of April, in the second indiction, aged about thirty years, in the reign of our most pious lord, the Emperor Justinian, in the fourth year of his consulship, in the second year of the pontificate of our Apostolic lord, Pope Sergius."
When Caedwalla went to Rome, Ini succeeded to the kingdom, being of the blood royal; and having reigned thirty-seven years over that nation, he in like manner left his kingdom and committed it to younger men, and went away to the threshold of the blessed Apostles, at the time when Gregory was pope, being desirous to spend some part of his pilgrimage upon earth in the neighbourhood of the holy places, that he might obtain to be more readily received into the fellowship of the saints in heaven. This same thing, about that time, was wont to be done most zealously by many of the English nation, nobles and commons, laity and clergy, men and women,