Amos 2:6
Thus says Yahweh: "For three transgressions of Israel, yes, for four, I will not turn away its punishment; because they have sold the righteous for silver, and the needy for a pair of shoes;
WEB
Thus saith the LORD; For three transgressions of Israel, and for four, I will not turn away the punishment thereof; because they sold the righteous for silver, and the poor for a pair of shoes;
KJV
What Amos 2:6 means
It is the prophet Amos accusing Israel's powerful of being so corrupt that they would sell off a poor person for the price of a pair of sandals.
Amos was a shepherd from the southern kingdom of Judah, sent north to Israel in the 700s BC, a time when the country was prosperous and comfortable. He arrives with a list of charges, and the phrase "for three transgressions, yes, for four" is his way of saying the wrongdoing has piled up past counting.
The specific crime here is economic. Judges were taking bribes to rule against honest people, and the poor were being handed into debt-slavery over debts as small as the cost of a pair of sandals. Naming that price is the whole point. It shows how cheaply the powerful had come to hold a human life. Amos insists that God sees this ordinary, market-day cruelty as clearly as any grander sin.