Who shall pray for him. By these words Heli would have his sons understand, that by their wicked abuse of sacred things, and of the very sacrifices which were appointed to appease the Lord, they deprived themselves of the ordinary means of reconciliation with God; which was by sacrifices. The more, because as they were the chief priests, whose business it was to intercede for all others, they had no other to offer sacrifice and make atonement for them. (Challoner)

We need not, however, consider the words of Heli as an oracle of God. (Sanchez)

In human transactions, a person would find more difficulty in obtaining pardon, when the judge himself had received the injury. Septuagint, instead of appeased, have “and they shall pray for him.” (Menochius)

Some may be found to plead his cause, but if he have offended the judge, who will undertake to be his advocate? What medicines shall be used, when those, which God has appointed, are trodden under foot? (Haydock)

By persevering in such wickedness, no redress can be expected: and indeed, the infinite distance between God and man, would place an insuperable obstacle to a reconciliation, if Jesus Christ had not undertaken the cause even of the most desperate sinner. (Calmet)

Because the Lord would slay them. In consequence of their manifold sacrileges, he would not soften their hearts with his efficacious grace, but was determined to destroy them. (Challoner)

They had filled up the measure of their crimes; and, though God wills not the death of a sinner, they had treasured up to themselves wrath, which he will now display. We might also translate ci, “therefore,” (Noldius; Osee ix. 15, &c.) or “that.” They would not be convinced that the threat of their father would be executed. (Schmid) (Calmet)

Sins directly against God, and which hinder his service, are remitted with greater difficulty, though to all true penitents pardon is promised, Ezechiel xxxiii. God did not take away the free will of Ophni and Phinees, but left them to their own obstinacy, and justly punished them. See St. Augustine, contra Jul. v. 3. (Worthington)

They had already rendered themselves unworthy of extraordinary graces. (Tirinus) (St. Thomas Aquinas, 1 p. q. 23, n. 3.)