Old Testament readings use the Septuagint , the Scripture the apostles quoted. Masoretic numbering shown for reference.Learn why
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Revelation 5:6

I saw in the middle of the throne and of the four living creatures, and in the middle of the elders, a Lamb standing, as though it had been slain, having seven horns and seven eyes, which are the seven Spirits of God, sent out into all the earth.

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