Passage 4.21.7
ἀλλὰ ὁ θεὸς τὸ ὕδωρ ἐπήγαγεν ἀθρόον μᾶλλον μετὰ ἰσχυροῦ τῶν βροντῶν τοῦ ψόφου καὶ τοὺς ὀφθαλμοὺς αὐτῶν ἐναντίαις ταῖς ἀστραπαῖς ἐξέπλησσε. τοῖς δὲ Λακεδαιμονίοις ταῦτα πάντα παρίστη φρόνημα, καὶ αὐτὸν ἀμύνειν σφίσιν ἔφασαν τὸν θεόν· καὶ---ἤστραπτε γὰρ τούτοις κατὰ δεξιὰ---ἀπέφαινεν Ἕκας ὁ μάντις ὡς αἴσιον εἴη τὸ σημεῖον.
But the god brought water upon them suddenly, accompanied by a mighty sound of thunder, and dazzled their eyes with flashes of lightning directed right against them. For the Lacedaemonians, all these events raised their spirits, and they declared that the god himself was fighting on their side; and indeed—since lightning flashed for them on the right—Hekas the seer interpreted this omen as favorable.