The second group mentioned in this verse is “the spirits of the righteous made perfect (teteleiomenon).” They live in heaven as persons without a body, just as the angels, who are also sometimes referred to as spirits (Hebrews 1:14). They are waiting for the day of the resurrection when they will receive a glorious new body. Think, for example, of the martyr Stephen in Jerusalem. When they stoned his body, he called out: Lord Jesus, receive my spirit.
They can kill his body, but not his soul (psuchѐ) (see the words of Jesus in Matthew 10:28). The spirit, as the inside,
the inner part of man, comes close to the soul. When the body dies, the soul is saved and taken up alive into heaven. Here one can also think of those believers who were killed (beheaded) because of their faith, but their souls
(psuchѐ) live on in heaven and sing to God (Revelation 5:9–10). These righteous ones are all these saints from Hebrews 11:1–40, who went before us and are now in heaven—the witnesses, who have finished the race and are now encouraging us from the stands (see Hebrews 12:1–2).
23 and to the assembly of the firstborn who are enrolled in heaven, and to God, the judge of all, and to the spirits of the righteous made perfect,