NET
1 Therefore we must pay closer attention to what we have heard, so that we do not drift away.
Darby
1 For this reason we should give heed more abundantly to the things [we have] heard, lest in any way we should slip away.
KJV
1 Therefore we ought to give the more earnest heed to the things which we have heard, lest at any time we should let [them] slip.