Charles Spurgeon Commentary Genesis 49:4

"Boiling over as water, thou shalt not have the pre-eminence; Because thou wentest up to thy father`s bed; Then defiledst thou it: he went up to my couch." — Genesis 49:4 (ASV)

Unstable as water, thou shalt not excel;

So it is clear that the greatest strength and dignity and power will not serve a man, so as to make him excel, if he is unstable.

There are many such persons still remaining in the world; their doctrine changes like the moon, and we never know what it is. Their spirit and temper constantly change; their pursuits are sometimes in one direction, and sometimes in another; they are "everything by starts, and nothing long;" and to each of them it may be said, Unstable as water, thou shalt not excel.

Unstable as water, thou shall not excel; because thou wentest up to thy father's bed; then defiledst thou it: he went up to my couch.

So a man may have great opportunities, and yet lose them.

Uncontrolled passions may make him very little who otherwise might have been great. Reuben was the excellency of dignity, and the excellency of power, yet his father had to say to him, Thou shalt not excel.