Will of the blessed Emperor Constantine
A year and a few months afterwards the emperor was taken ill at Nicomedia, a city of Bithynia, and, knowing the uncertainty of human life, he received the holy rite of baptism, which he had intended to have deferred until he could be baptized in the river Jordan.
He left as heirs of the imperial throne his three sons, Constantine, Constantius, and Constans, the youngest.
He ordered that the great Athanasius should return to Alexandria, and expressed this decision in the presence of Eusebius, who did all he could to dissuade him.
Source: Ecclesiastical History (New Advent)