Cyprian of Carthage, Three Books of Testimonies Against the Jews III.102: That the Holy Spirit has frequently appeared in fire

In Exodus: “And the whole of Mount Sinai smoked, because God had come down upon it in fire.” Also in the Acts of the Apostles: “And suddenly there was made a sound from heaven, as if a vehement blast were borne along, and it filled the whole of that place in which they were sitting. And there appeared to them cloven tongues as if of fire, which also settled upon each of them; and they were all filled with the Holy Ghost.” Also in the sacrifices, whatsoever God accounted accepted, fire descended from heaven, which consumed what was sacrificed. In Exodus: “The angel of the Lord appeared in a flame of fire from the bush.”