'Slip' in the Bible

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.

This hope [this confident assurance] we have as an anchor of the soul [it cannot slip and it cannot break down under whatever pressure bears upon it]—a safe and steadfast hope that enters within the veil [of the heavenly temple, that most Holy Place in which the very presence of God dwells],