As a strict deadline approaches, the people of Yabesh Gilead employ a clever military tactic against the Ammonites. The seven-day waiting period has just ended with the return of their messengers. Knowing that rescue will only arrive the following day, the residents desperately need to buy a little more time [מלבי״ם, ביאור שטיינזלץ]. To achieve this, they deliver a carefully crafted message designed to deceive the enemy into lowering their guard, creating the perfect opportunity for a surprise attack.
The communication relies entirely on double-speak. On the surface, the Ammonites understand the message as a promise of complete surrender [ביאור שטיינזלץ]. However, the hidden truth behind the declaration is a promise of war. By offering to present themselves to the enemy the following day, the people of Yabesh secretly intend to launch a battle, turning a seemingly weak submission into a strategic trap [מלבי״ם].