Therefore (dia touto). Because Jesus is superior to prophets and angels and because the new revelation is superior to the old. The author often pauses in his argument, as here, to drive home a pungent exhortation. Ought (dei). It is necessity, necessity rather than obligation (crh). To give heed (prosecein). Present active infinitive with noun (accusative singular of nou) understood as in Acts 8:6 . More earnest (perissoterw). Comparative adverb, "more earnestly," "more abundantly" as in 1 Thessalonians 2:7To the things that were heard (toi akousqeisin). Dative plural neuter of the articular participle first aorist passive of akouw. Lest haply we drift away (mh pote pararuwmen). Negative clause of purpose with mh pote and the second aorist passive subjunctive of pararrew, old verb to flow by or past, to glide by, only here in N.T. (cf. Proverbs 3:21 ). Xenophon (Cyrop. IV. 52) uses it of the river flowing by. Here the metaphor is that "of being swept along past the sure anchorage which is within reach" (Westcott), a vivid picture of peril for all ("we," hma).