A.T. Robertson Commentary Revelation 2:14

"But I have a few things against thee, because thou hast there some that hold the teaching of Balaam, who taught Balak to cast a stumblingblock before the children of Israel, to eat things sacrificed to idols, and to commit fornication." — Revelation 2:14 (ASV)

There (εκε). That is παρ' υμιν (among you). A party in the church that resisted emperorworship, to the death in the case of Antipas, yet were caught in the insidious wiles of the Nicolaitans which the church in Ephesus withstood.

Some that hold (κρατουντας). "Men holding" (present active participle of κρατεω).

The teaching of Balaam (την διδαχην Βαλααμ). Indeclinable substantive Balaam (Numbers 25:1–9; 31:15f.). The point of likeness of these heretics with Balaam is here explained.

Taught Balak (εδιδασκεν τω Βαλακ). Imperfect indicative of διδασκω, Balaam's habit, "as the prototype of all corrupt teachers" (Charles). These early Gnostics practised licentiousness as a principle since they were not under law, but under grace (Romans 6:15). The use of the dative with διδασκω is a colloquialism rather than a Hebraism. Two accusatives often occur with διδασκω.

To cast a stumbling-block (βαλειν σκανδαλον). Second aorist active infinitive (accusative case after εδιδασκεν) of βαλλω, regular use with σκανδαλον (trap) like τιθημ σκανδαλον in Ro 14:13. Balaam, as Josephus and Philo also say, showed Balak how to set a trap for the Israelites by beguiling them into the double sin of idolatry and fornication, which often went together (and do so still).

To eat things sacrificed to idols (φαγειν ειδωλοθυτα). Second aorist active infinitive of εσθιω and the verbal adjective (from ειδωλον and θυω), quoted here from Nu 25:1f. , but in inverse order, repeated in other order in verse 20. See Ac 15:29; 21:25; 1 Corinthians 8:1ff. for the controversy over the temptation to Gentile Christians to do what in itself was harmless, but which led to evil if it led to participation in the pagan feasts. Perhaps both ideas are involved here. Balaam taught Balak how to lead the Israelites into sin in both ways.