παράκλητος
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
English (LSJ)
ον,
A called to one's aid, in a court of justice : as Subst., legal assistant, advocate, D.19.1, Lycurg. Fr.102, etc. 2 summoned, δοῦλοι D.C.46.20, cf. BGU601.12 (ii A.D.). II intercessor, Ph.2.520 : hence in NT, Παράκλητος, of the Holy Spirit, Ev.Jo.14.16, cf. 1 Ep.Jo.2.1.
German (Pape)
[Seite 483] zu Hülfe gerufen, hülfreich, bes. vor Gericht, advocatus, als subst. Sachwalter, Dem. 19, 1; auch der für Einen bittet, Sp., vgl. D. L. 4, 50; N. T.