Faced with a cruel ultimatum, the elders of a besieged city do not simply beg for mercy; they execute a calculated strategic move. They ask for a seven-day truce, requesting that the enemy pause the attack and wait [מצודת דוד, ביאור שטיינזלץ, מצודת ציון]. This brief window of time is needed to send messengers throughout the entire land of the Israelites [ביאור שטיינזלץ]. The elders promise that if they cannot find anyone to come to their rescue, they will leave the safety of their city and surrender completely, allowing the enemy to do with them as he pleases [רלב״ג, ביאור שטיינזלץ].
The primary approach among commentators explains why such a ruthless attacker would agree to a pause. The enemy's original intention was to bring deep disgrace upon all the Israelites. The elders skillfully use this to their advantage, arguing that a quiet, unknown surrender would fail to achieve this goal. There is no national shame if the rest of the nation is unaware of the siege. True disgrace can only be achieved if the Israelite tribes are fully informed of the danger, yet either fail in their rescue attempt or stand by in helpless silence. Only under those circumstances would the people of Yavesh accept the humiliation [מלבי״ם, מצודת דוד, אברבנאל].
Pleased by this logic, the enemy grants the requested time. He believes this delay will serve his ultimate ambition: drawing all the Israelites into a massive war so he can conquer their entire land. However, his arrogance proves to be his undoing. The seven-day truce provides exactly enough time for the messengers to reach Saul, who successfully mobilizes the Israelites, delivers a crushing defeat to the Ammonite forces, and scatters their army completely [רלב״ג].