John Gill Commentary 1 Kings 13:30

"And he laid his body in his own grave; and they mourned over him, [saying], Alas, my brother!" — 1 Kings 13:30 (ASV)

And he laid his carcass in his own grave
Which he had prepared for himself; for, as he came from Samaria, it could not be the sepulchre of his fathers; and this was showing all the respect, and doing all the honour to him, he well could:

and they mourned over him ;
the prophet and his sons: saying,

alas, my brother ;
which was an usual form of lamentation at funerals in later times, see (Jeremiah 22:18) .