Old Testament readings use the Septuagint , the Scripture the apostles quoted. Masoretic numbering shown for reference.Learn why
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Revelation 8:12

The fourth angel sounded, and one third of the sun was struck, and one third of the moon, and one third of the stars, so that one third of them would be darkened; and the day wouldn’t shine for one third of it, and the night in the same way.

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