Nicene and Post-Nicene Fathers, Vol. III:
Moral Treatises of St. Augustin: Section 10

10. Ever, my brother, in such cases, it behoves with fear to recollect, “Whoso shall deny Me before men, I will deny him before My Father which is in heaven.” 2394 Or truly is it no denying of Christ before men, to deny Him before Priscillianists, that when they hide themselves, one may by a blasphemous lie strip them and catch them? But who doubts, I pray thee, that Christ is denied, when so as He is in truth, we say that He is not; and so as the Priscillianist believes Him, we say that He is?

Footnotes

Matt. 10.33