Saint John did not absolutely forbid that prayer should be made for those who "sin unto death," since he knew that Moses, Jeremiah, and Stephen had so prayed, and he himself implies that forgiveness is not to be denied them. Such intercessors, then, must be sought for after very grievous sins, for if any ordinary persons pray they are not heard. . . Stephen prayed for his persecutors, who had not been able even to listen to the Name of Christ, when he said of those very men by whom he was being stoned: "Lord, lay not this sin to their charge" And we see the result of this prayer in the case of the Apostle, for Paul, who kept the garments of those who were stoning Stephen, not long after became an apostle by the grace of God, having before been a persecutor.
St. Ambrose of Milan