
The horns have elicited various interpretations. The likeliest explanation is that Michelangelo relied on Jerome's vulgate translation of the Old Testament. The "rays of light "karan ohr" that were seen around Moses' face after his meeting with God on Mt Sinai were expressed as horns. Some people believe that Jerome's intention was to express a metaphor for the glory of God reflected from Moses's face. The mistake in translation is possible because the word "keren" in the Hebrew language can mean either "ray" or "horn".
1 Corinthians 10
1 For I do not want you to be ignorant of the fact, brothers, that our forefathers were all under the cloud and that they all passed through the sea. 2 They were all baptized into Moses in the cloud and in the sea. 3 They all ate the same spiritual food 4 and drank the same spiritual drink; for they drank from the spiritual rock that accompanied them, and that rock was Christ. 5 Nevertheless, God was not pleased with most of them; their bodies were scattered over the desert.
6 Now these things occurred as examples to keep us from setting our hearts on evil things as they did. 7 Do not be idolaters, as some of them were; as it is written: "The people sat down to eat and drink and got up to indulge in pagan revelry." 8 We should not commit sexual immorality, as some of them did—and in one day twenty-three thousand of them died. 9 We should not test the Lord, as some of them did—and were killed by snakes. 10 And do not grumble, as some of them did—and were killed by the destroying angel.
11 These things happened to them as examples and were written down as warnings for us, on whom the fulfillment of the ages has come. 12 So, if you think you are standing firm, be careful that you don't fall! 13 No temptation has seized you except what is common to man. And God is faithful; he will not let you be tempted beyond what you can bear. But when you are tempted, he will also provide a way out so that you can stand up under it.