And another angel came and stood at the altar, having a golden censer; and there was given unto him much incense, that he should offer it with the prayers of all saints upon the golden altar which was before the throne. And the smoke of the incense, which came with the prayers of the saints, ascended up before God out of the angel's hand. (Rev 8:3-4)
In the book of Revelation, there are a few passages where heavenly beings, whether angels or the disembodied spirits of the “elders” are said to offer prayers to God. While they were not the recipients of prayers (that is, people were not praying to/through them), evidenced by their also said to being in possession of orbs containing the wrath of God (Rev 15:7), it does show God's use of instruments in prayer, salvation, and judgment. Indeed, in Jewish traditions, angels help bring prayers of believers on earth to God. As Howard Schwartz wrote:
God’s Crown of Prayers
Three times each day the prayers of Israel ascend on high. When all of Israel has finished praying, what happens to their prayers? They thread their way to Paradise, to the highest heaven, where they are gathered by the angel Sandalphon, the angel appointed over prayers. Sandalphon collects all the prayers that have been offered in all the synagogues, and waves them into garlands of prayer that he places upon the head of God, to wear on His Throne of Glory. That is why it is said that God is crowned with the prayers of Israel.
The idea that God wears a crown is a natural development from the concept of God as king. Since kings were the highest, most powerful human figures, God was viewed as the ultimate king. So too does God have a throne, the Throne of Glory, and a crown. The notion of God wearing a crown is also reinforced by the biblical verse; and a splendid crown upon Your head (Ezek. 16:12).
Here, though, the crown is formed in a wonderful way. The angel Sandalphon, charged with gathering the prayers of Israel, first collects the prayers and then weaves them into crowns of prayer. In some versions the angel puts the crown directly on God. In others, the angel pronounces an adjuration that causes the crown to rise on its own and settle on God’s head.
Sources:
B. Hagigah 12a, 13b; Exodus Rabbah 21:4; Pesikta Rabbati 19:7; Beit ha-Midrash 1:58-61; Midrash Konen in Beit ha-Midrash 2:26; Sefer ha-Komah; Seder Tkhines u-Vakoshes 3.
Studies:
Keter: The Crown of God in Early Jewish Mysticism by Arthur Green (Howard Schwartz, Tree of Souls: The Mythology of Judaism [Oxford: Oxford University Press, 2004], )