ξενοτρόφος
From LSJ
οὐκ ἂν λάβοις παρὰ τοῦ μὴ ἔχοντος → you can't take from one who doesn't have, you can't squeeze blood out of a turnip, you can't get blood out of a turnip, you can't get blood from a stone, you can't get blood out of a stone
German (Pape)
[Seite 278] Gastfreunde, Fremde ernährend, Miethssoldaten haltend, VLL.