Dora Bas Rivka Silver O'H
What's a Plumb Line?
G-d showed Amos what He had in store; G-d was gathering locusts for a swarm. When the prophet saw the locusts devouring everything (in his vision), he prayed to G-d to forgive the people, since no one could save them from the devastation the locusts would cause. How could the tiny remainder of the nation survive? G-d accepted Amos' prayer and agreed not to send the swarm.
Next, G-d showed Amos a great, devouring conflagration. (This could literally be a fire or it could be a symbol for war and pestilence. The Radak says it's a heat wave, leading to a drought.) Again, Amos begged G-d not to send this punishment and, again, G-d agreed.
Then, G-d showed Amos a vision of His Glory, standing on a wall holding a plumb line. (A plumb line is a weighted string, used to test verticals, similar to the way a level is used to test horizontals.) G-d said He would use the plumb line to judge the people strictly and that He would not forgo any more punishments. The land would become desolate and ruined and the dynasty of Yeravam (Jeroboam II) will be cut off. (Oddly, here Amos refers to the nation as Yitzchak - Isaac - rather than Israel or Jacob. This may be a reference to the Akeidah - the binding of Isaac - or to Isaac's other son, Esau.)
Amatzya, the priest of the idol at Beth-El, got wind of the prophecies Amos was relating and he sent word to Yeravam, king of Israel. (Remember, this was the second king by that name, so don't be confused!) Amatzya accused Amos of treason for the things he was saying about the nation and the king. Amatzya even embellished Amos' words, saying things the prophet never said. (For example, Amatzya quoted Amos as saying that Yeravam would die by the sword. Amos never said that, nor is that how Yeravam died. Amatzya was trying to incite the king against the prophet.)
Amatzya warned Amos to get out of Beth-El and to go to Judah, where they might appreciate his brand of prophecy. Amos replied that he is not like one of Amatzya's false prophets, who prophesy for pay. He owns herds and groves. He has money, so he doesn't do this to make a living; he does it because G-d told him to! Amatzya can't bully Amos out of doing G-d's will!
Since Amatzya tried to silence G-d's prophet from rebuking His people, he would be punished. His wife would willingly cheat on him with enemy soldiers from the invading force and his children would be cut down by the enemy sword. Amatzya's land would be divvied up by the invaders and he would die in captivity.