Charles Ellicott Commentary Genesis 35:22

"And it came to pass, while Israel dwelt in that land, that Reuben went and lay with Bilhah his father`s concubine: and Israel heard of it. Now the sons of Jacob were twelve:" — Genesis 35:22 (ASV)

Reuben. —Again, another grief was to mar Jacob's return home; this time it arises from the sin of his firstborn, who thereby forfeits the birthright. It was the thought of these miseries, following his long years of exile, that made Jacob speak so sorrowfully of his life experience before Pharaoh (Genesis 47:9).

And Israel heard it. —The Masora notes that some words are missing from the text here, which the Septuagint supply by adding, And it was evil in his sight.