What did Reuben do that Jacob later brought up on his deathbed?
Reuben, Jacob’s eldest, committed adultery with one of Jacob’s wives. The matter seemingly remained unspoken until Jacob’s deathbed, when Jacob recalled it while blessing his twelve sons, declaring that Reuben would not receive the birthright or blessing and would not be esteemed as the eldest because of that sin.
Les explains that when Jacob pronounced blessings on his twelve sons, he began with Reuben, the eldest, and brought Reuben’s sin to mind. Reuben was the most unchaste and promiscuous of the sons and committed adultery with one of Jacob’s wives. According to the context, nothing was evidently said about it until old Jacob’s deathbed. At that time Jacob declared that Reuben would not have the birthright or the blessing and would not be esteemed as the eldest because he had committed adultery with one of his wives. Les notes that seemingly no one else ever knew it.