1 John 3:19

19byἐνthisτούτῳwe will knowγνωσόμεθαthatὅτιofἐκtheτῆςtruthἀληθείαςwe areἐσμέν,andκαὶbeforeἔμπροσθενHimαὐτοῦwe will assureπείσομενtheτὴνheartκαρδίανof usἡμῶν

And in this we will know that we are of the truth, and we will assure our heart before Him,