Old Testament readings use the Septuagint , the Scripture the apostles quoted. Masoretic numbering shown for reference.Learn why
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Esther 2:12

Each young woman’s turn came to go in to King Ahasuerus after her purification for twelve months (for so were the days of their purification accomplished, six months with oil of myrrh, and six months with sweet fragrances and with preparations for beautifying women).

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