From Dom Guéranger's The Liturgical Year.
To this Collect of the Vigil let us add, with the holy liturgy, the commemoration of a holy confessor, whose imprisonment and sufferings at Rome, in the time of the Arians, made him well nigh equal to the martyrs. As he is honoured with a church in the Eternal City, Eusebius is entitled to the homage of the whole world.
Prayer
Deus, qui nos beati Eusebii, Confessoris tui, annua solemnitate lætificas: concede propitius; ut, cujus natalitia colimus, per ejus ad te exempla gradiamur. Per Dominum.
O God, who givest us joy by the annual solemnity of the blessed Eusebius, Thy Confessor, mercifully grant that, celebrating his festival, we may approach to Thee by following his example. Through our Lord, etc.