Genesis 49:4 - Wesley's Explanatory Notes

Thou shalt not excel — A being thou shalt have as a tribe, but not an excellency. No judge, prophet, or prince, are found of that tribe, nor any person of renown only Dathan and Abiram, who were noted for their impious rebellion. That tribe, as not aiming to excel, chose a settlement on the other side Jordan. The character fastened upon Reuben, for which he is laid under this mark of infamy, is, that he was unstable as water. His virtue was unstable, he had not the government of himself, and his own appetites. His honour consequently was unstable, it vanished into smoke, and became as water spilt upon the ground. Jacob charges him particularly with the sin for which he was disgraced, thou wentest up to thy father's bed — It was forty years ago that he had been guilty of this sin, yet now it is remembered against him. Reuben's sin left an indelible mark of infamy upon his family; a wound not to be healed without a scar.