Extended Strong's Greek Lexicon (Abbott-Smith based)
be truthful
Usage: ἀληθεύω (ἀληθής), [in LXX: Gen.20:16 (יָכַח) Gen.42:16 (אֶמֶת), Pro.21:3 (מִשְׁפָּט), Isa.44:26 (שָׁלַם), Sir.34:4 * ;] to speak the truth (R, mg., deal truly; Field, Notes, 192): Gal.4:16, Eph.4:15.† (AS)