John Gill Commentary Genesis 11:12

"And Arpachshad lived five and thirty years, and begat Shelah." — Genesis 11:12 (ASV)

And Arphaxad lived thirty five years, and begat Salah .
] Arphaxad is the first on record that had a son born to him so early; of Salah, (See Gill on Genesis 10:24).