συμμάχομαι
From LSJ
καὶ οὐκ ἐκδικᾶταί σου ἡ χείρ, καὶ οὐ μηνιεῖς τοῖς υἱοῖς τοῦ λαοῦ σου καὶ ἀγαπήσεις τὸν πλησίον σου ὡς σεαυτόν· ἐγώ εἰμι κύριος. Τὸν νόμον μου φυλάξεσθε → Let your hand not seek vengeance; do not show wrath toward the children of your people; love your neighbor as yourself. I am the Lord! Keep my Torah! (Leviticus 19:18f. LXX)
English (LSJ)
fut.
A -οῦμαι X.An.5.4.10: aor. συνεμαχεσάμην Aeschin.2.169:—fight along with others, to be an ally, auxiliary, Th.4.44, 8.26, Pl.Lg.699a, X.HG 3.2.13: c. dat., Id.An.5.4.10, 6.1.13; τὸ οἰκὸς ἐμοὶ συμμάχεται probability is on my side, Hdt.7.239; σ. πρὸς τὸν δῆμον against... Arist. Pol.1300a18; σ. τὴν μάχην Aeschin. l.c.—Prose word, συμμαχέω being used by Poets.