'one hundred forty-four thousand, sealed out of every tribe of the people of Israel' (v. 4)
'a great multitude ... from all tribes and peoples and languages.'
'These are those who have come out of the great ordeal' (v. 14).
In turn, the Godness of God which is confirmed through the resurrection validates the promise Jesus the good shepherd makes here about his sheep not being snatched away: neither shepherd nor sheep are subject to another power, together they form the imperishable flock of God.
Footnote: John 10:29 is a little tricky. Should it read, as the NRSV main text has it:
What my Father has given me is greater than all else, and no one can snatch it out of the Father's hand.
Or, should it read (with different ancient authorities), what it has as a footnote,
My Father who has given them to me is greater than all, and no one can snatch them out of the Father's hand.
This equals what the REB makes its main text!
The latter smoothes out a difficulty in the former, which on a basic principle of textual criticism means the former (as the more difficult reading) is more likely to be original. But the original is very difficult to understand (What is the "what"/"it" which the Father has given Jesus?). Is it at all possible that the original writer has made a mistake and the correction is actually what he intended to say? The latter version is nicely consistent with what is (indisputedly) written in verse 28!