προεγγυάομαι
From LSJ
Περὶ τοῦ ἐπέκεινα τοῦ νοῦ κατὰ μὲν νόησιν πολλὰ λέγεται, θεωρεῖται δὲ ἀνοησίᾳ κρείττονι νοήσεως → On the subject of that which is beyond intellect, many statements are made on the basis of intellection, but it may be immediately cognised only by means of a non-intellection superior to intellection
English (LSJ)
A furnish security or guarantee, Milet.3No.138.42 (iii B.C.):—Pass., App.Fr.1.1.
