There is a hint of it in Genesis 49:29....
“And when Jacob made an end of charging his sons, he gathered up his feet unto the bed, and expired, and was gathered to his people.”
If we take that to mean the souls who had gone before, (which I believe), then it only makes sense to pray that that reunion be as wonderful as God can make it.
At least to me.
WHY would we need to pray that the reunion is as wonderful as God can make it?
Couldn’t GOD come up with the idea all on His own?
But WAIT!!
there's MORE!
When I go; I'll be gathered to mine as well: in the GraveYard!
The Scriptures mention dead folks...
Daniel 12:2
Multitudes who sleep in the dust of the earth will awake: some to everlasting life, others to shame and everlasting contempt.
Ecclesiastes 9:1-6
1 But all this I laid to heart, examining it all, how the righteous and the wise and their deeds are in the hand of God. Whether it is love or hate, man does not know; both are before him.
2 It is the same for all, since the same event happens
to the righteous and the wicked,
to the good and the evil,
to the clean and the unclean,
to him who sacrifices and him who does not sacrifice.
As the good one is, so is the sinner, and
he who swears is as he who shuns an oath.
3 This is an evil in all that is done under the sun, that the same event happens to all. Also, the hearts of the children of man are full of evil, and madness is in their hearts while they live, and after that they go to the dead. 4 But he who is joined with all the living has hope, for a living dog is better than a dead lion.
5 For the living know that they will die, but the dead know nothing, and they have no more reward, for the memory of them is forgotten. 6 Their love and their hate and their envy have already perished, and forever they have no more share in all that is done under the sun.