προεγγυάομαι
From LSJ
Ubi idem et maximus et honestissimus amor est, aliquando praestat morte jungi, quam vita distrahi → Where indeed the greatest and most honourable love exists, it is much better to be joined by death, than separated by life.
English (LSJ)
furnish security or guarantee, Milet.3No.138.42 (iii B.C.):—Pass., App.Fr.1.1.