Wiktionary
argumentum ad lazarum
n. An appeal to poverty; the logical fallacy of thinking a conclusion is correct because the speaker is poor.
Wikipedia
Argumentum ad lazarum
Argumentum ad lazarum or appeal to poverty is the formal fallacy of thinking a conclusion is correct because the speaker is poor, or it is incorrect because the speaker is rich. It is named after Lazarus, a beggar in a New Testament parable who receives his reward in the afterlife.
This is popularly exploited as the statement, "Poor, but honest."
The opposite is the argumentum ad crumenam.