Anyone who realizes that his brother has sinned, with a sin that is not unto death, let him pray, and life shall be given to him who has sinned not unto death. There is a sin which is unto death. I am not saying that anyone should ask on behalf of that sin
Other versions
King James Version
If 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.English Standard Version
If anyone sees his brother committing a sin not leading to death, he shall ask, and God will give him life--to those who commit sins that do not lead to death. There is sin that leads to death; I do not say that one should pray for that.New International Version
If anyone sees his brother commit a sin that does not lead to death, he should pray and God will give him life. I refer to those whose sin does not lead to death. There is a sin that leads to death. I am not saying that he should pray about that.