A.T. Robertson Commentary 2 Peter 1:18

"and this voice we [ourselves] heard borne out of heaven, when we were with him in the holy mount." — 2 Peter 1:18 (ASV)

This voice (ταυτην την φωνην). The one referred to in verse 17.We heard (ηκουσαμεν). First aorist active indicative of ακουω, a definite experience of Peter.

Brought (ενεχθεισαν). "Borne" as in verse 17.When we were with him (συν αυτω οντες). Present active participle of ειμ, "being with him."

In the holy mount (εν τω αγιω ορε). Made holy by the majestic glory. See Eze 28:14 for "holy mount of God," there Sinai, this one probably one of the lower slopes of Hermon. Peter's account is independent of the Synoptic narrative, but agrees with it in all essentials.