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
dĕ-hăbĕo: ēre,
I v. a., not to have, to lack (late Lat.), Hier. Ep. 22, no. 35.