1 We have now to consider these words of the Lord, “Verily, verily, I say unto you, If you shall ask anything of the Father in my name, He will give it you.” It has already been said in the earlier portions of this discourse of our Lord's, on account of those who ask some things of the Father in Christ's name and receive them not, that there is nothing asked of the Father in the Saviour's name that is asked in contrariety to the method of salvation. For it is not the sound of the letters and syllables, but what the sound itself imports, and what is rightly and truly to be understood by that sound, that He is to be regarded as declaring, when He says, “in my name.”
Hence, he who has such ideas of Christ as ought not to be entertained of the only Son of God, asks not in His name, even though he may not abstain from the mention of Christ in so many letters and syllables; since it is only in His name he asks, of whom he is thinking when he asks. But he who has such ideas of Him as ought to be entertained, asks in His name, and receives what he asks, if he asks nothing that is contrary to his own everlasting salvation. And he receives it when he ought to receive it.
For some things are not refused, but are delayed till they can be given at a suitable time. In this way, surely, we are to understand His words, “He will give you,” so that thereby we may know that those benefits are signified which are properly applicable to those who ask. For all the saints are heard effectively in their own behalf, but are not so heard in behalf of all besides, whether friends or enemies, or any others: for it is not said in a general kind of way, “He will give;” but, “He will give you.”
Source: Tractates on the Gospel of John (New Advent)