I saw in heaven another great and miraculous sign. Seven angels were about to bring the seven last plagues. The plagues would complete God's anger.
References for Revelation 15:1
Then I saw something that looked like a sea of glass mixed with fire. Standing beside the sea were those who had won the battle over the beast. They had also overcome his statue and the number of his name. They held harps given to them by God.
They sang the song of Moses, who served God, and the song of the Lamb. They sang, "Lord God who rules over all, everything you do is great and wonderful. King of the ages, your ways are true and fair.
Lord, who will not have respect for you? Who will not bring glory to your name? You alone are holy. All nations will come and worship you. They see that the things you do are right."
After this I looked, and the temple was opened in heaven. The temple is the holy tent where the tablets of the covenant were kept.
Out of the temple came the seven angels who were bringing the seven plagues. They were dressed in clean, shining linen. They wore gold strips of cloth around their chests.