The great word that follows may hang closely on the "because" of John 14:12. Whether that be so or not, the power of their hands to perform these greater works is in answer to prayer presented to himself, and their success is nothing less than his own activity.
And whatsoever ye ask in my Name, that will I do (see Luther). Here for the first time our Lord uses these words. Frequently (John 5:43; John 10:25) he had spoken of the Father's Name, and in Matthew 18:20 εἰς τὸ ἐμὸν ὄνομα occurs; but now he suggests a new and vitalizing condition of prayer.
Luthardt has suggested that the believer, being "in Christ," prays to the Father, who is also in Christ. But the ἐν is used here in two entirely distinct senses. Others have said, taking "Name" as the compendium of all his perfections, that asking "in his Name" meant in full recognition of his Person and his relation to them and to the Father.
The Name of the Son reveals the Father, and by assuming this most excellent Name, and having its fullness of meaning avouched by the Resurrection and Ascension, the Father was truly manifested. Others, again, urge that Christ's "Name" is equivalent to "himself;" and "in my Name" means "in the full consciousness that he is the element in which prayerful activity lives and moves" (Meyer).
Surely this passage is the true justification of prayer to Christ himself, as identically one with the Father (see Revelation 7:17). "This thing I will do" is strongly in favor of this interpretation.
That the Father may be glorified in the Son. The end of this prayer-offering and the Lord's response is that the Father may be glorified; the Father who has such a Son is thereby glorified in the grateful love of his children, and in the Son himself, who is seen thus to be the link between him and his other children.