In the book of Revelation, the apostle John saw a vision of a great multitude in heaven (Rev. 19:1-5). John's vision in heaven takes place at the end of the great tribulation, when God's wrath is poured out on the earth. This vision likewise takes place immediately before the second coming of our Lord and Savior Jesus Christ.
What did John see in this vision? He saw the great multitude of heaven. That multitude included the redeemed of God, as well as the angels. The redeemed are represented by the 24 elders, representing all the redeemed of God. Twenty-four is a number that represents all of God's people. It includes the twelve patriarch's of the Old Testament, a symbol for the twelve tribes of Israel. The twenty-four also includes the twelve apostles of the Lamb, representing the church of the Lord Jesus Christ.
What did John hear through the vision? The multitude was praising God in worship. They praised God for His salvation and righteous judgment upon the ungodly. The key word of praise was Hallelujah. That word literally means "praise Jehovah." Worship focuses upon praising God for who He is, what He has done, and what He shall do.
John's vision is a great testimony to the sovereignty of our God. He who knows the end from the beginning has power over all. Our salvation is to His glory! His judgments are righteous and just. Our future as the redeemed of God is under His control, power and dominion. God Almighty rules and reigns over all. Hallelujah!