ἐπιμαρτύρεσθαι
From LSJ
ἀλλὰ διὰ τῆς ἀγάπης δουλεύετε ἀλλήλοις. ὁ γὰρ πᾶς νόμος ἐν ἑνὶ λόγῳ πεπλήρωται, ἐν τῷ Ἀγαπήσεις τὸν πλησίον σου ὡς σεαυτόν → but be enslaved to each other through love; for the whole Torah is fulfilled in one statement: You will love your neighbor as yourself (Galatians 5:13f.)
Greek > English (Woodhouse Verbs Reversed)
(see also ἐπιμαρτύρομαι): conjure, invoke, call in as witness, call on as witness, call on, call to witness, call upon
Lexicon Thucydideum
obtestari, to beseech, 6.29.2 (de Alcibiade concerning Alcibides).