“Looking diligently lest any man fail of the grace of God; lest any root of bitterness springing up trouble you, and thereby many be defiled;”
King James Version (KJV)
12:15 Looking diligently, lest any one - If he do not lift up the hands that hang down. Fall from the grace of God: lest any root of bitterness - Of envy, anger, suspicion. Springing up - Destroy the sweet peace; lest any, not following after holiness, fall into fornication or profaneness. In general, any corruption, either in doctrine or practice, is a root of bitterness, and may pollute many.
Heb 12:15 Looking diligently lest any man fail of the grace of God. Being careful that no one lags behind and falls by the way so as not to reach the final reward. Lest any root of bitterness springing up trouble [you]. Any bitter opposition, or element of disturbance causing members to sin.