Therefore neither Abraham, nor Isaac, nor Jacob, nor any other man, saw the Father and ineffable Lord of all, and also of Christ, but [saw] Him who was according to His will His Son, being God, and the Angel because He ministered to His will; whom also it pleased Him to be born man by the Virgin; who also was fire when He conversed with Moses from the bush.
Justin Martyr
Dialogue with Trypho
Chapter CXXVII