When a foreign prophet attempts to curse the Israelites, God actively intervenes in the revelation process. Instead of allowing the prophet to speak as he pleases, God takes control, ensuring that blessings reach the ears of the Moabite king exactly as planned, completely overriding the prophet's original, malicious intentions.
The exact nature of how God placed His message into the prophet's mouth is a matter of deep discussion. One tradition suggests a physical, forceful control. According to this view, an angel or an iron nail was placed in his throat; he was given the freedom to bless, but the moment he attempted to curse, his mouth was physically blocked [תורה תמימה]. A second approach views this intervention as a spiritual barrier. Because the prophet was an impure man with low moral character, and divine prophecy is inherently holy, God created a partition. The message placed in his mouth served as a buffer, preventing the holy spirit from passing directly through an unclean vessel [אור החיים].
In contrast to the idea of physical or spiritual coercion, other commentators argue that the prophet did not speak as an empty, unconscious tool. Rather, God taught him the prophecy, explained its meaning, and rehearsed it with him thoroughly so he would memorize it with perfect precision, never forgetting or omitting a single word [רמב״ן, הטור הארוך, העמק דבר, רש״ר הירש]. Another perspective suggests he did not receive exact words to recite at all. Instead, he was given a broad conceptual message that he was required to formulate into his own words for the king [ביאור שטיינזלץ]. Internally, this entire process reflects the progressive stages of prophetic achievement: absorbing inner knowledge, experiencing spiritual elevation, and finally revealing hidden truths to the outside world [אדרת אליהו].
The explicit instruction to return to the king was designed to force the prophet to stand directly before him and deliver the message to his face. This direct confrontation was meant to deeply frustrate the king, forcing him to listen as blessings were showered upon the Israelites [אור החיים].
The narrative does not immediately detail the exact contents of this divine conversation. This omission is deliberate. The Torah chose not to dwell on a prophetic dialogue with a wicked man, withholding the honor typically reserved for the prophets of Israel. Instead, it relies on the fact that the message will become clear when it is actually spoken to the king [ריב״א, חזקוני]. Furthermore, the specific instruction of how to speak echoes the ancient promise given to Abraham that his offspring would multiply. The prophet was commanded to inform the king that because God had already decreed the vast expansion of the Israelites, any attempt to destroy or harm them was entirely futile [דעת זקנים, ריב״א].