Old Testament readings use the Septuagint , the Scripture the apostles quoted. Masoretic numbering shown for reference.Learn why
LXX

Isaiah 40:9

O thou that bringest glad tidings to Zion, go up on the high mountain; lift up thy voice with strength, thou that bringest glad tidings to Jerusalem; lift it up, fear not; say unto the cities of Juda, Behold your God!

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