Revelation 10:7 But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as he hath declared to his servants the prophets.

Which mystery of God is this referring to?

Are we not to be stewards of the mysteries of God?

I Corinthians 4:1 Let a man so account of us, as of the ministers of Christ, and stewards of the mysteries of God.

So which mystery of God is mentioned in Revelation 10:7?