Proverbs 27:1-2

Do not strut about tomorrow as if you owned it — you do not even know what today will bring before nightfall. Now read this carefully, because it is easy to twist. It does not forbid planning for tomorrow; providing wisely for the future is a Christian duty, and the believer who plans while leaning on God's providence is walking with God. What it forbids is the boast — the casual presumption that "tomorrow shall be as this day" (Isaiah 56:12), which quietly puts God out of His own world. "Go to now, ye that say, To day or to morrow we will go into such a city... whereas ye know not what shall be on the morrow... ye ought to say, If the Lord will" (James 4:13–15). Haman walked out one morning expecting honor and was hanged before evening. And there is a sharper edge for anyone "boasting of tomorrow" in the one matter that counts: the man who keeps promising he will get serious about God later. Tomorrow is the devil's great ally, the very Goliath he trusts for victory — and now is the little stripling God sends out against him. The world will gladly agree to be Christian tomorrow, if Christ will only let it be worldly today. Do not boast of a day you may never see: "now is the accepted time" (2 Corinthians 6:2). You never feel more secure than when you know you have no security for a single hour — and rest it all on God.

Verse 2 turns to a smaller vanity that exposes the same heart: do not be your own publicist. Let someone else praise you — better still, a stranger with no reason to flatter — and never your own mouth. Self-praise degrades the one who indulges it; your works, not your tongue, should publish your worth, as John the Baptist let his life speak. Self-seeking is a shameful blot on a Christian profession; let your hands do the boasting and keep your lips quiet.