Revelation 5:8

8 Now when he had taken the book, the four living creatures and the twenty-four elders fell down before the Lamb, each one having a harp, and golden bowls full of incense, which are the prayers of the saints. 

Revelation 8:3-6

3 Another angel came and stood over the altar, having a golden censer. Much incense was given to him, that he should add it to the prayers of all the saints on the golden altar which was before the throne.  4 The smoke of the incense, with the prayers of the saints, went up before God out of the angel's hand.  5 The angel took the censer, and he filled it with the fire of the altar, and threw it on the earth. There followed thunders, sounds, lightnings, and an earthquake.

6 The seven angels who had the seven trumpets prepared themselves to sound.