Bridges on Proverbs 27:1
Charles Bridges on Proverbs 27:1

1.  Boast not thyself of to morrow; for thou knowest not what a day may bring forth. {to...: Heb. to morrow day}
LET the Apostle expound the wise man — “Go to now, ye that say — To-day or to-morrow we will go into such a city, and continue there a year, and buy and sell, and get gain.” Both apply the same rebuke to the boast; Thou knowest not what a day may bring forth — Whereas “ye know not what shall be on the morrow.” (James 4:13, 14.) To provide for the morrow is a scriptural duty.† The husbandman, when he has reaped his harvest, sows his seed for the next. The Christian in his calling, reposing on God’s Providence, walks with God. But to boast of to-morrow — “all such rejoicing is evil.” (James 4:16.) Indeed it is absurd to boast of what is not our own. To-morrow is finely described as an unknown birth. It may be in eternity. And yet the sensualist and the worldling† boast, as if it was their own; and thus virtually put God out of his own world. The ungodly reckon upon being religious to-morrow, and therefore put off repentance, forsaking the world, and living for eternity, to some infinitely future day. (Acts 24:25.) Would they do this if they did not reckon upon to-morrow being given to them? Nay, do we not all naturally cherish this looking forward, which the great enemy works up into practical forgetfulness of God? Yet we must not live as if to-morrow would not come. Else would the world be in a state of stagnation. The present duties of the day would be absorbed in the instant preparation for the coming eternity. But we start† from death when he enters our houses, as if we did not expect him. How little do we die daily! (1 Corinthians 15:31.) We can even coolly calculate upon the death of others for our own benefit. Our intense anxiety about earthly, and apathy about heavenly things, speak but too plainly. The young look to the middle age; the more advanced to the last stage of life. All, in contradiction to their avowed profession, boast themselves of to-morrow.
How awfully has this boasting been put to shame! In the days of Noah, “they married wives, and were given in marriage, until the very day when the flood came, and destroyed them all.”† Abner promised a kingdom, but could not ensure his life for an hour.† Haman plumed himself upon the prospect of the queen’s banquet, but was hanged like a dog before night.† The fool’s soul was required of him “on the very night” of his worldly projects “for many years” to come.† ‘Serious affairs to-morrow’ — was the laughing reply of Archias, warned of a conspiracy which hurried him into eternity the next hour.† The infidel Gibbon calculated upon fifteen years of life, and died within a few months, at a day’s warning. We know not what a day may bring forth.
How natural is it for the young to be looking for to-morrow’s prospect! But have you never seen the lovely flower cropped, or faded in the blossom? Is not the robust, as well as the feeble, frame cut down in the prime? (Job 21:23.) Have you a lease of your life? If there be a promise of forgiveness to the repenting, where is the promise of to-morrow for repentance? Will consideration naturally come with years? Or will not rather long-protracted habits of ungodliness harden into a second nature? What if in the midst of thy boasting, flattering thyself that thou shouldst see another and another day — thou shouldst be surprised, unprepared, and be left to lament for ever thy presumption in the lake of everlasting fire!† Stop — consider — weep — pray — believe — now — while conscience speaks; while thou art halting between God and the world, between conviction and inclination. Now in this “accepted time” devote thyself to God. Enthrone the Savior in thine heart.
The universe does not present a more affecting sight than an aged sinner, with one foot in the grave, losing all in the world, infinitely more in eternity. A moment, and he is gone. Heaven and hell are no trifles. To-morrow presumed upon, to-day neglected, ruins all. Standing on the brink of the precipice — how precious the moment for prayer — ere the door of mercy is closed for ever!
Has the child of God reason to boast of to-morrow? What a change may it make in your worldly circumstances (Job 1:21), or Christian experience? (Psalm 30:7.) Never will you feel more secure, than in the consciousness that you have no security for a single hour. Divide your cares with God. Rest all in his bosom. (Ib. 37:4.) Let disappointment prepare you for your heavenly rest, and bound all your wishes and pleasures by his gracious will. (James 4:15.) But have you no need of warning? How speaks the too full current of affections towards earthly enjoyment? Did you practically believe that “the time is short, and the fashion of this world passeth away,” would you not “rejoice, as though you rejoiced not”? (1 Corinthians 7:29-32.) Would pleasures of earth be so highly prized, if there was no secret dependence on to-morrow? Surely this thought may more than sustain in the loss of them — The shadow only is gone — the body of my happiness remains immovable. To see things temporal, as if we “looked not at them,” is the life of spiritual religion. (2 Corinthians 4:18.) To remember ‘this world as the grand laboratory for perfecting of souls for the next’† to have “our loins girt about” for our Lord’s coming; to live, as not to be surprised by the call, and in readiness to “open to him immediately” — this is our secret and our happiness. “Blessed are those servants, whom the Lord, when he cometh, shall find watching.” (Luke 12:37.)