And I heard the number of the sealed, 144,000, sealed from every tribe of the sons of Israel:
12,000 from the tribe of Judah were sealed,
12,000 from the tribe of Reuben,
12,000 from the tribe of Gad,
12,000 from the tribe of Asher,
12,000 from the tribe of Naphtali,
12,000 from the tribe of Manasseh,
12,000 from the tribe of Simeon,
12,000 from the tribe of Levi,
12,000 from the tribe of Issachar,
12,000 from the tribe of Zebulun,
12,000 from the tribe of Joseph,
12,000 from the tribe of Benjamin were sealed.
After this I looked, and behold, a great multitude that no one could number, from every nation, from all tribes and peoples and languages, standing before the throne and before the Lamb, clothed in white robes, with palm branches in their hands,
and crying out with a loud voice, “Salvation belongs to our God who sits on the throne, and to the Lamb!” (Revelation 7:4-10)
The 144,000 consisted of 12,000 from each of the 12 tribes of Israel. The number 12 is used symbolically in the Bible to refer to Israel, and so this crowd is symbolic of a large crowd of Israelites.
Notice that John heard the crowd described in this way as coming from the tribes of Israel, but when he looks at the crowd he sees they are from every nation on earth. This is a typical feature in Revelation where what is described is different from is seen, but the two are connected. For example, John is told “Behold the lion of the tribe of Judah” (Rev 5:5) but when he looks he sees a lamb (Rev 5:6). Both the lion and the lamb represent Jesus.
The same literary device is used in Revelation 7. John hears that there is a huge crowd of Israelites who are “sealed” as belonging to God, but he sees a huge crowd of people from every nation. It is the same crowd, identified as Israelites because they are God’s people, even though they actually come from all nations of the earth. They represent the faithful believers in God’s kingdom. The number 144,000 should not be taken literally — it is simply used to indicate a large number of people, and the 144=12×12 suggests they are “Israelites”, i.e., God’s people.