Esther 3:5-7

When Haman saw that Mordecai neither bowed down nor paid homage to him, he was furious. But he disdained laying hands on Mordecai alone, for they had told him who the people of Mordecai were (his nationality); so Haman determined to destroy all the Jews, the people of Mordecai, who lived throughout the kingdom of Ahasuerus. In the first month, the month of Nisan (Mar-Apr), in the twelfth year of King Ahasuerus, Haman cast Pur, that is, the lot, cast before him day after day [to find a lucky day to approach the king], month after month, until the twelfth month, the month of Adar (Feb-Mar).