A.B. Simpson, quoted by Andree Seu in World:

God is represented as treasuring the prayers of his saints in vials.... They are placed like fragrant flowers in the chambers of the king.... And later they are represented as poured out upon the earth; and lo, there are voices, and thunderings, and great providential movements, fulfulling God's purposes for His kingdom. We are called 'The Lord's Remembrances.' And we are commanded to give Him no rest, day or night, but to crowd the heavens with our petitions.

And in due time the answer will come with its accumulated blessings. No breath of prayer is lost. The longer it waits, the larger it becomes.

(Hat tip to our friends at Wittingshire)