Charles Spurgeon Commentary John 8:39

"They answered and said unto him, Our father is Abraham. Jesus saith unto them, If ye were Abraham`s children, ye would do the works of Abraham." — John 8:39 (ASV)

They answered and said to him, Abraham is our father. Jesus says to them, If you were Abraham’s children, you would do the works of Abraham.

That is, if you were the true spiritual children of faithful Abraham, you would act as he did.