Exodus xxxiv. 30, “All the children of Israel saw Moses, and the skin of his face shone, ” translated in the Vulgate, “Cornuta esset facies sua.” Rays of light were called horns. Hence in Habakkuk (iii. 4) we read of God, “His brightness was as the light, and He had horns [rays of light ] coming out of His hand.” Michel Angelo depicted Moses with horns, following the Vulgate.
The French translation of Habacue, iii. 4 is:
“Sa splendeur etait comme la lumière meme, et des rayons sortaient de sa main.”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894