From the Tanakh, Bereshit 25:8
And Abraham expired, and died in a good old age, an old man, and full of years; and was gathered to his people.

From the KJV Bible, Genesis 25:8
Then Abraham gave up the ghost, and died in a good old age, an old man, and full of years; and was gathered to his people.

There are several places in both the Tanakh and the so-called "Old Testament" of the Bible that say that when people die, they are gathered to their people. Needless to say, these are people who have already died.

And we are not talking about one's body being buried together with the bodies of one's people.