Albert Barnes Commentary 1 John 5:15

"and if we know that he heareth us whatsoever we ask, we know that we have the petitions which we have asked of him." — 1 John 5:15 (ASV)

And if we know that He hears us. This means that if we are assured of this as a true doctrine, then, even though we may not immediately see that the prayer is answered, we may have the utmost confidence that it is not disregarded. We can be sure that it will be answered in the way best adapted to promote our good.

The specific thing we request may not indeed be granted (2 Corinthians 12:8–9), but the prayer will not be disregarded. Instead, what is most for our good will be bestowed upon us.

The argument here is derived from the faithfulness of God—from the assurance we have that when He has promised to hear us, there will be, sooner or later, a real answer to the prayer.

We know that we have the petitions. This evidently means that we know we shall have them, or that the prayer will be answered. It cannot mean that we already have the precise thing for which we prayed, or that it will be an immediate real answer to the prayer, for these reasons:

1. The prayer may relate to something future, such as protection on a journey, a harvest, restoration to health, the safe return of a son from a sea voyage, or the salvation of our souls. All of these are future and cannot be expected to be granted at once.
2. The answer to prayer is sometimes delayed, though ultimately granted. There may be reasons why the answer should be deferred, as the promise is not that it will be immediate. The delay may arise from causes such as these:
   1. To test our faith and see whether the blessing is earnestly desired.
   2. Perhaps it could not be answered at once without a miracle.
   3. It might not be consistent with God's arrangements concerning others to grant it to us at once.
   4. Our own condition may not be such that it would be best to answer it at once. We may need further trial or further chastisement before the affliction, for example, is removed. Consequently, the answer to the prayer may be delayed for months or years. Yet, in the meantime, we may have the firmest assurance that the prayer is heard and that it will be answered in the way and at the time when God sees it to be best.