Passage 3.7.5
Θεόπομπον δὲ τὸν Νικάνδρου βασιλεύσαντα μετὰ Νίκανδρον μέλλει καὶ αὖθις ὁ λόγος μοι προσθήσειν προελθόντι ἐς τὴν Μεσσηνίαν συγγραφήν. Θεοπόμπου δὲ ἔτι ἔχοντος τὴν ἀρχὴν ἐν Σπάρτῃ γίνεται καὶ ὁ περὶ τῆς Θυρεάτιδος καλουμένης χώρας Λακεδαιμονίοις ἀγὼν πρὸς Ἀργείους, Θεόπομπος δὲ αὐτὸς οὐ μετέσχε τοῦ ἔργου γήρᾳ καὶ ὑπὸ λύπης τὸ πλέον· Ἀρχίδαμον γὰρ Θεοπόμπου ζῶντος ἔτι ἐπιλαμβάνει τὸ χρεών.
Theopompus, son of Nicander, who became king after Nicander, will be mentioned again by me later on, when my narrative progresses to the account of Messenia. While Theopompus was still reigning in Sparta, the contest concerning the district called Thyreatis arose between the Lacedaemonians and the Argives; but Theopompus himself did not take part in this battle, being prevented mostly by old age and grief. Indeed, during Theopompus' lifetime, Archidamus succeeded him in authority.