{4} See then that ye walk circumspectly, not as fools, but as wise,

(4) The worse and more corrupt that the manners of this world are, the more watchful we ought to be in every situation, and give regard to nothing but the will of God.

People's New Testament

5:15 See then that ye walk circumspectly. The Revised Version makes the meaning clear: Look therefore carefully how ye walk.

Wesley's Notes

5:15 Circumspectly - Exactly, with the utmost accuracy, getting to the highest pitch of every point of holiness. Not as fools - Who think not where they are going, or do not make the best of their way.

Jamieson-Fausset-Brown Bible Commentary

15. that-rather as Greek, "See how ye walk," &c. The double idea is compressed into one sentence: "See (take heed) how ye walk," and "See that ye walk circumspectly." The manner, as well as the act itself, is included. See how ye are walking, with a view to your being circumspect (literally, accurate, exact) in your walk. Compare Col 4:5, "Walk in wisdom (answering to 'as wise' here) toward them that are without" (answering to "circumspectly," that is, correctly, in relation to the unbelievers around, not giving occasion of stumbling to any, but edifying all by a consistent walk).

not as fools-Greek, "not as unwise, but as wise."

Matthew Henry's Concise Commentary

5:15-21 Another remedy against sin, is care, or caution, it being impossible else to maintain purity of heart and life. Time is a talent given us by God, and it is misspent and lost when not employed according to his design. If we have lost our time heretofore, we must double our diligence for the future. Of that time which thousands on a dying bed would gladly redeem at the price of the whole world, how little do men think, and to what trifles they daily sacrifice it! People are very apt to complain of bad times; it were well if that stirred them more to redeem time. Be not unwise. Ignorance of our duty, and neglect of our souls, show the greatest folly. Drunkenness is a sin that never goes alone, but carries men into other evils; it is a sin very provoking to God. The drunkard holds out to his family and to the world the sad spectacle of a sinner hardened beyond what is common, and hastening to perdition. When afflicted or weary, let us not seek to raise our spirits by strong drink, which is hateful and hurtful, and only ends in making sorrows more felt. But by fervent prayer let us seek to be filled with the Spirit, and to avoid whatever may grieve our gracious Comforter. All God's people have reason to sing for joy. Though we are not always singing, we should be always giving thanks; we should never want disposition for this duty, as we never want matter for it, through the whole course of our lives. Always, even in trials and afflictions, and for all things; being satisfied of their loving intent, and good tendency. God keeps believers from sinning against him, and engages them to submit one to another in all he has commanded, to promote his glory, and to fulfil their duties to each other.