Library Eusebius of Caesarea Life of Constantine
Book 4, Chapter 13: He bespeaks his Affectionate Interest for the Christiansin his Country.
Imagine, then, with what joy I heard tidings so accordant with my desire, that the fairest districts of Persia are filled with those men on whose behalf alone I am at present speaking, I mean the Christians. I pray, therefore, that both you and they may enjoy abundant prosperity, and that your blessings and theirs may be in equal measure; for thus you will experience the mercy and favor of that God who is the Lord and Father of all. And now, because your power is great, I commend these persons to your protection; because your piety is eminent, I commit them to your care. Cherish them with your wonted humanity and kindness; for by this proof of faith you will secure an immeasurable benefit both to yourself and us.
English translation by Ernest Cushing Richardson, in Nicene and Post-Nicene Fathers, Series II, Vol. I (eds. Philip Schaff and Henry Wace; Buffalo: Christian Literature Publishing Co., 1890). Public domain. Digital text via New Advent Church Fathers.