A.T. Robertson Commentary John 14:2

"In my Father`s house are many mansions; if it were not so, I would have told you; for I go to prepare a place for you." — John 14:2 (ASV)

Mansions (μονα). Old word from μενω, to abide, abiding places, in N.T. only here and verse 23. There are many resting-places in the Father's house (οικια). Christ's picture of heaven here is the most precious one that we possess. It is our heavenly home with the Father and with Jesus.

If it were not so (ε δε μη). Ellipsis of the verb (Revelation 2:5,16; John 14:11). Here a suppressed condition of the second class (determined as unfulfilled) as the conclusion shows.

I would have told you (ειπον αν υμιν). Regular construction for this apodosis (αν and aorist--second active--indicative).

For I go (οτ πορευομα). Reason for the consolation given, futuristic present middle indicative, and explanation of his words in 13:33 that puzzled Peter so (13:36f.).

To prepare a place for you (ετοιμασα τοπον υμιν). First aorist active infinitive of purpose of ετοιμαζω, to make ready, old verb from ετοιμος. Here only in John, but in Mr 10:40 (Matthew 20:23). It was customary to send one forward for such a purpose (Numbers 10:33). So Jesus had sent Peter and John to make ready (this very verb) for the passover meal (Matthew 26:17). Jesus is thus our Forerunner (προδρομος) in heaven (Hebrews 6:20).