He hasn't disciplined them I Samuel 3:13
I suspect that Eli's problem was laziness. All through this narrative we are told of his problem with obesity. In this spot in the story it says that he failed to discipline his children. He couldn't be bothered to shape their character, that would require too much effort, anyway "boys will be boys" right? Eli's bulk made him a slow moving vehicle, unable and perhaps unwilling to lead his children. He let them go their own way. "They will figure it out" he thought to himself, as he remained seated, stuck to his chair, munching on yet another lamb chop.
Laziness is the passive form of selfishness. Those who possess it in large quantities will not be a part of God's kingdom no matter how religious they are, or how nice they are. To be a dad and to be lazy or disinterested about that responsibility is truly one of the great tragedies of humanity.
In 20 years of pastoral work, I see this problem to be among the most damaging for human flourishing. God help me to not shirk my responsibility to be a loving, involved dad, who is absolutely committed to the hard but wonderful work of shaping my children's character.