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

Isaiah 30:15

Thus saith the Lord, the Holy Lord of Israel; When thou shalt turn and mourn, then thou shalt be saved; and thou shalt know where thou wast, when thou didst trust in vanities: [then] your strength became vain, yet ye would not hearken:

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