What did Apostle Paul say about that in 1 Timothy 1?
Paul was instructing Timothy to "charge some that they teach no other doctrine" (v 3). That is, no doctrine other than the Gospel of Christ, which opposes the doctrine of justification by the works of the law, for "the law is not of faith." The law does not consist of faith in Christ, nor is faith necessary to follow the law, for nowhere does it require it.
Bible Commentary by John Gill-- "But the man that doth them shall live in them." The passage referred to, is in Leviticus 18:5, the word "them," relates to the statutes and judgments, not of the ceremonial, but of the moral law. The Jewish doctors observe on those words, that "it is not said, priests, Levites, and Israelites, but Mdah, "the man"; lo, you learn from hence, that even a Gentile that studies in the law, is as an high priest.
"So that whatever man does the things contained in the law, that is, internally as well as externally, for the law is spiritual, reaches the inward part of man, and requires truth there, a conformity of heart and thought unto it, and that does them perfectly and constantly, without the least failure in matter or manner of obedience, such shall live in them and by them.
"The language of the law is, do this and live, so life and the continuation of that happy natural life which Adam had in innocence, was promised to him, in case of his persisting in his obedience to the law; and so a long and prosperous life was promised to the Israelites in the land of Canaan, provided they observed the laws and statutes which were commanded them: but since eternal life is a promise made before the world began, is provided for in an everlasting covenant, is revealed in the Gospel, and is the pure gift of God's grace through Christ, it seems that it never was the will of God that it should be obtained by the works of the law, and which is a further proof that there can be no justification in the sight of God by them, see Galatians 3:21." JG