The law of sowing and reaping
«Do not be deceived, God is not mocked; for whatever a man sows, that he will also reap. For he who sows in his flesh will of the flesh reap corruption, but he who sows to the Spirit will of the Spirit reap everlasting life» (Galatians, 6:7-8).
«For if you live according to the flesh you will die; but if by the Spirit you put to death the deeds of the body, you will live»(Romans, 8: 13)