1 Thessalonians 3:5
For this cause, when I could no longer forbear, I sent to know your faith, lest by some means the tempter have tempted you…
An enemy, before he besiegeth a city, surroundeth it at a distance to see where the wall is weakest, best to be battered, lowest, easiest to be scaled; ditch narrowest to be bridged, shallowest to be waded over; what place, if not regularly fortified, where he may approach with least danger, and assault with most advantage. So Satan walketh about surveying all the powers of our souls, where he may most probably lay his temptations, — as whether our understandings are easier corrupted with error, or our fancies with levity, or our wills with frowardness, or our affections with excess.
Parallel VersesKJV: For this cause, when I could no longer forbear, I sent to know your faith, lest by some means the tempter have tempted you, and our labour be in vain.