שְׁתֵּ֤ים עֶשְׂרֵה֙ שָׁנָ֔ה עָבְד֖וּ אֶת־כְּדָרְלָעֹ֑מֶר וּשְׁלֹשׁ־עֶשְׂרֵ֥ה שָׁנָ֖ה מָרָֽדוּ׃
Twelve years they served Chedorlaomer, and in the thirteenth year they rebelled.
Read midrashic interpretation of Genesis 14:4: and classical rabbinic exegesis.