After failing to convince King Jeroboam to execute Amos, Amaziah takes a direct approach to intimidate the prophet and drive him out of the Kingdom of Israel. Approaching Amos under the guise of a concerned friend, Amaziah warns him that the king might kill him and advises him to flee for his life [אבן עזרא, מלבי״ם, אברבנאל]. He addresses Amos as a seer, acknowledging his ability to foresee the future [רש״י, מצודת ציון, שטיינזלץ], and urges him to return to his native land of Judah [שטיינזלץ].
Amaziah presents Judah as the natural and proper setting for prophecy because it is home to God's Temple [רש״י, מצודת דוד]. He points out that in Judah, unlike in the Kingdom of Israel, true prophets of God are welcome, and the people will receive his words with love and without putting him in danger [אברבנאל].
Embedded in this seemingly helpful advice is a deep layer of mockery. The primary approach among commentators is that Amaziah implies Amos is driven by financial motives, much like false prophets who invent predictions just to earn a meal. Amaziah suggests that the people of Judah will gladly pay and feed him for delivering harsh predictions against their rival kingdom of Israel [מצודת דוד, רד״ק]. Another perspective views this remark as practical advice stemming from a severe famine in Israel at the time, suggesting that Amos would only be able to find enough food if he returned to Judah [אברבנאל].
Ultimately, Amaziah makes it entirely clear that Amos has no future in Israel. Whether the prophet's true goal is to earn a living or to genuinely guide the people back to the right path, his efforts in Israel will achieve nothing. Only in Judah will he be left alone to deliver his message to an audience willing to listen [מלבי״ם, שטיינזלץ].