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14And this is the confidence that we have in him, that, if we ask any thing according to his will, he heareth us: 15And if we know that he hear us, whatsoever we ask, we know that we have the petitions that we desired of him. 16If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it. 17All unrighteousness is sin: and there is a sin not unto death.
1 John 5:14-17 (KJV)