ἀμφισβητεῖν
From LSJ
ἐπέμψατε ἀγγέλους τοῖς ἀλλήλοις ὥστε ἔγνωτε τὸν κίνδυνον → you sent messengers to one another so that you knew the danger
Greek > English (Woodhouse Verbs Reversed)
(see also ἀμφισβητέω): dispute, argue with, contest a claim, discuss with, dispute with, raise difficulties, waver in mind