For example in Amos 7:12 (NAB), it is written:
To Amos, Amaziah said: "Off with you, seer, flee to the land of Judah and there earn your bread by prophesying!"
How did Old Testament prophets "earn their bread?"
For example in Amos 7:12 (NAB), it is written:
To Amos, Amaziah said: "Off with you, seer, flee to the land of Judah and there earn your bread by prophesying!"
How did Old Testament prophets "earn their bread?"
We do know how at least some of the prophets earned their living.
Pastors and farmers. Amos himself says he is not professional prophet but insists "I am a herdsman and a dresser of sycamores." (Amos 7:14) Several of the earliest prophets were pastors: Abraham, Isaac and Jacob being the most famous of these, and they also produced grain and wine (Genesis 27:37). David, of course, had been a shepherd when he composed some of the prophetic psalms attributed him. Elisha had been plowing at his family's farm when he was called to his prophetic ministry (1 Kings 19:19). It is possible that he returned there between missions.
Priests. Ezra and Ezekiel were both priests. When the Temple altar was functioning, they received portions of the sacrificial offerings. In Jerusalem, priests were often quite wealthy. Ezra was a descendant of the the high priest Seraiah (Neh. 8:13) and his family's wealth probably sustained him and his family during the Exile. Ezekiel lived in a colony by the River Chebar (Ezekiel 1:2-4) and was likely supported by the community there. While there, God instructed him in the baking of bread (ch. 4), which he did daily for more than a year (this act had symbolic meaning as well as providing sustenance.) Ezra also received support from King Ataxerxes (Ezra 7:11ff) to raise donations to rebuild the Temple. Jeremiah, though apparently not a priest himself, came from a priestly family that owned land. (see below) Much earlier, Samuel had been both a prophet and a priest. The episode mentioned in @Dottard's answer (1 Sam 9:6-8), in which pilgrims bring a gift of food to him, may be typical of prophets in rural settings.
Court prophets. Later prophets sometimes earned their sustenance as advisers to kings. Unfortunately this could lead to corruption. The priest of Bethel, Amaziah, hints at this when he advises Amos to ply his trade in Judah, where the kings were more likely to receive him. Some court prophets, such as Isaiah, were faithful ministers of God, while others simply told the king what he wanted to hear. 1 Kings 22:7-8 dramatically demonstrates this when king Ahab of Israel admits, after 400 prophets have supported his plan: “There is one other man through whom we might consult the Lord; but I hate him because he prophesies not good but evil about me." The prophet Daniel can be seen as a court prophet in Nebuchadnezzer's household. He and his friends received royal food (accepting only vegetables) at the king's expense and then entered the kings service (1:19). The same may be said of the patriarch Joseph who became the grand vizier of Egypt as a result of his prophecies to the pharaoh.
Guilds. The "sons of the prophets" (which Amos, for one, did not join) were sometimes bands of roaming ecstatic bards who prophesied with the aid of musical instruments in various shrines and high places (1 Samuel 10:10). Samuel travelled to several such shines as a kind of circuit minister. The prophet Ahijah was associated especially with the sanctuary at Shiloh (1 Kings 14:2). Britannica says: "Members of those guilds generally prophesied for money or gifts and were associated with such sanctuaries as Gibeah, Samaria, Bethel, Gilgal, Jericho, Jerusalem, and Ramah. Jeremiah mentions [ch 35] that the chief priest of Jerusalem was the supervisor of both priests and prophets and that those prophets had rooms in the Temple buildings."
Scribes. Literate prophets could also work as scribes. Although only Ezra is designated by this title, we can speculate that some others did work at this trade professionally when not engaged in their prophetic activities.
Landowners. Jeremiah came from a priestly family of landowners in Anathoth; and he did not marry, so his needs were relatively modest. Later, he invested in a field at God's advice, based on the prediction that "They shall again purchase houses and fields and vineyards in this land. (Jeremiah 32:15) Unfortunately, Jeremiah did not live long enough to see this prophecy realized.
Kings. Some prophets were also kings, notably Saul, David and Solomon.
Gifts from God and the people. The Bible also relates several instances of God feeding the prophets, such as by sending ravens to feed Elijah, (1 Kings 17:4), or Elisha's miraculous multiplying of loaves (2 Kgs. 4). God provided the prophets Moses, Aaron and Miriam (as well as the other Israelites) with manna for 40 years while they were in the wilderness (Ex. 16:35). I Kings 7 also shows that people in the countryside brought offering to prophets or otherwise gave them hospitality. So does 1 Kings 17, where God directs the prophet to the house of a widow, who provides food and lodging. As with the case of Samuel, such hospitality was likely not exceptional for well-known men of God.
Wives and Mothers. Finally, female prophets such as Miriam, Deborah and Huldah relied on their husbands or brothers for their "daily bread." Miriam and Deborah were also community leaders and no doubt received many invitations to eat with families and clans; and in Miriam's case God provided her and her brother prophets with manna and quails as well.
The summary above shows some of the ways in which prophets earned their living or were supported by God and the people. There are also a few hints about professional knowledge (Zechariah knew construction for example). In general, the professional activities of the prophets were diverse, ranging from working as shepherds and farmers to serving as priests, singers, musicians, scribes, court advisers and even kings.
The short answer to the question is, We do not know because we are not told. However, we get a hint in one place like 1 Sam 9:6-8
“Look,” said the servant, “in this city there is a man of God [the prophet Samuel] who is highly respected; everything he says surely comes to pass. Let us go there now. Perhaps he will tell us which way to go.”
“If we do go,” Saul replied, “what can we give the man? For the bread in our packs is gone, and there is no gift to take to the man of God. What do we have?”
The servant answered him again. “Look,” he said, “I have here in my hand a quarter shekel of silver. I will give it to the man of God, and he will tell us our way.”
Thus, in the case of the prophet Samuel (at least) divine advice was dispensed for a voluntary fee. After that, the prophet relied on charity and the providence of God as was the case with Elijah during the drought (1 Kings 17:1-7).
The speech quoted is made by Amaziah, priest of Bethel, who is an opponent of Amos and the speech is sarcastic.
Then Amaziah the priest of Bethel sent a message to Jeroboam king of Israel: “Amos is raising a conspiracy against you in the very heart of Israel. The land cannot bear all his words." [...] Then Amaziah said to Amos, “Get out, you seer! Go back to the land of Judah. Earn your bread there and do your prophesying there. Don’t prophesy anymore at Bethel, because this is the king’s sanctuary and the temple of the kingdom.” (Amos 7:10-13)
The NIV translates it as "Earn your bread there and do your prophesying there." Even if the NAB translation is correct, Amaziah is not making a practical, sensible suggestion but telling Amos stop prophesying here - to go somewhere else and do whatever he does there instead.
While several other answers have talked about how prophets earned a living, the scripture in the question is about something more.
Amos was "not a prophet" in the usual sense. He “took care of sycamore trees.” (Amos 7:14 NWT) But Jehovah God had chosen Amos to deliver a message to the northern ten-tribe kingdom of Israel.
Chapter 7 discusses the interaction between Amos and Amaziah "the priest of Bethel.” (Amos 7:10 NWT) Paragraph 16 of the article "Speak God's Word With Boldnes in the Nov. 15, 2004 issue of the Watchtower brings to light Amaziah's response to Amos' message:
Amaziah told Amos: “O visionary, go, run your way off to the land of Judah, and there eat bread, and there you may prophesy. But at Bethel you must no longer do any further prophesying, for it is the sanctuary of a king and it is the house of a kingdom.” (Amos 7:12, 13) In effect, Amaziah said: ‘Go home! We have our own religion.’ He also tried to get the government to ban the activities of Amos, telling King Jeroboam II: “Amos has conspired against you right inside the house of Israel.” (Amos 7:10) Yes, Amaziah accused Amos of treason! He told the king: “This is what Amos has said, ‘By the sword Jeroboam will die; and as regards Israel, it will without fail go into exile from its own ground.’”—Amos 7:11.
Other commentators have given similar information:
And there eat bread, &c. — There they will feed thee well, because thou pretendest to be a prophet.
there eat bread—You can earn a livelihood there, whereas remaining here you will be ruined.
There eat bread: thou wilt never get thy bread here by this kind of preaching; in Judah it is likely thou mayst get thy livelihood by thy prophetic art; thither go,
and there eat bread, and prophesy there: he took him for a mercenary man like himself, and that he prophesied for bread; which he intimates he would never be able to get in the land of Israel, but in all probability might in the land of Judea.
eat bread] i.e. make thy living. Amaziah implies that prophecy was a trade or profession. . . . "Which say to the seers, See not; and to the prophets, Prophesy not to us right things, speak to us smooth things, prophesy deceits:") (Isaiah’s political teaching was obnoxious to the people, and they would not listen to him: they wished for ‘seers’ who would “see” for them “smooth things,” i.e. visions of material prosperity, the success of their own plans, &c.);
Eat bread. Amaziah speaks, as if Amos was paid for his prophecies, made a gain of godliness.
So the scripture in question is more about Amaziah opposing the message that Amos was delivering by decree of Jehovah God.