Genesis 25:22

And the children struggled together within her; and she said, if it be so, why am I thus? And she went to enquire of the Lord. This was after pregnancy had advanced to the point that movement was distinctly felt. Fearing that her condition would result in misfortune to herself and probably to the child of promise, Rebekah, rash in her speech and actions, and easily discouraged, cried out: If this be so, what is the object of my still being here? Why should I still be living, with this sore and strange struggle within me? Nevertheless she went to ask the Lord, probably through the ministry of Abraham.

And it came to pass, when Israel dwelt in that land, that Reuben went and lay with Bilhah, his father's concubine; and Israel heard it. Bilhah was Rachel's hand-maid, but nevertheless Jacob's concubine; hence Reuben's sin was that of incest, not to speak of an utter lack of filial reverence. The matter was brought to the attention of the father, and although Jacob did not act at once, the punishment was eventually forthcoming, for the sin cost Reuben his birthright, Genesis 49:4. Now the sons of Israel were twelve: