1 Chronicles 5:1-2

The oldest son of Israel was Reuben. But since he dishonored his father by sleeping with one of his father’s concubines, his birthright was given to the sons of his brother Joseph. For this reason, Reuben is not listed in the genealogical records as the firstborn son. The descendants of Judah became the most powerful tribe and provided a ruler for the nation, but the birthright belonged to Joseph.