προεγγυάομαι
From LSJ
Οὕτως ἔδειξέν μοι κύριος καὶ ἰδοὺ ἐπιγονὴ ἀκρίδων ἐρχομένη ἑωθινή, καὶ ἰδοὺ βροῦχος εἷς Γωγ ὁ βασιλεύς (Amos 7:1) → Thus the Lord showed me and look, early-morning offspring of locusts coming, and look, one locust-larva: Gog the king.
English (LSJ)
A furnish security or guarantee, Milet.3No.138.42 (iii B.C.):—Pass., App.Fr.1.1.