Hebrews 12:15

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;

Lest any man fail, [ husteron (G5305)] - 'lest any (namely, through sloth in running) failing (falling short) of the grace of God ... trouble you.' The image is from travelers, one of whom lags behind, and so never reaches the end of the labourious journey (Chrysostom).

Root of bitterness. A bitter root might possibly bring forth sweet fruits; a root whose essence is "bitterness," never could. Paul refers to Deuteronomy 29:18. [Bleek infers from enochlee (G1776) of Alexandrine manuscript being here, not encholee of Vatican manuscript, that Paul used the Alexandrine text of the Septuagint (cf. Acts 8:23).] Every person (cf. Hebrews 12:16) and every principle so radically corrupt as to spread corruption around.

Many, [ hoi (G3588) polloi (G4183)] - 'the many;' i:e., the whole congregation. So long as it is under the earth it cannot be remedied, but when it 'springs up,' it must be dealt with boldly. Still remember the caution (Matthew 13:26) as to rooting out persons. No such danger can arise in rooting out bad principles.