A spiritual leader and father carries a heavy burden of responsibility, and remaining silent in the face of injustice extracts an irreversible price. The divine decree against the family of Eli the High Priest is sealed not merely because of the sins committed by his sons, but primarily due to his own failure to act firmly when he knew of their wrongdoing. God's message to Eli comes after a prophet had already delivered a prior warning. The initial warning was intended to leave an opening for repentance and correction. However, because Eli heard the prophet's words yet remained indifferent and failed to cry out against his sons' actions, the judgment is now finalized with an oath. The decree becomes absolute, with no possibility of turning back [מלבי״ם, מצודת דוד, חומת אנך].
The resulting punishment is an eternal sentence of shortened lifespans and disgrace for Eli's descendants. God reads the generations in advance and knows that no future generation in this family will possess enough merit to erase the sins of their ancestors [רד״ק]. The core of the offense lies in the sons' behavior and the father's awareness of it. Their actions are generally understood as showing a profound lack of reverence, bringing disgrace and disrespect upon the Tabernacle [רש״י, מצודת ציון, רד״ק, ביאור שטיינזלץ]. Alternatively, their behavior caused actual cursing; Eli knew that the Israelites were cursing his sons because they extorted the sacrifices and treated the women who came to the Tabernacle with shameful laziness and abuse [רלב״ג].
The primary approach among commentators is that the sons actually disgraced God directly, and that a scribal euphemism was employed in the historical record out of respect for Him [רש״י, מנחת שי, רד״ק]. Conversely, another view maintains that the situation was entirely literal: through their evil deeds, the sons brought the curse and disgrace upon themselves, transforming their own honor into deep shame [מלבי״ם, חומת אנך].
Eli's primary guilt is rooted in his failure to properly discipline his sons. He avoided casting a dark shadow over them, refusing to shame them publicly or strip them of their high and powerful positions [רש״י, מצודת דוד, מצודת ציון]. Although Eli did offer a gentle rebuke in his old age, the commentators agree that this soft approach did not fulfill his duty. He was obligated to protest forcefully from the very beginning, actively stop their actions, and strictly scold them the moment he heard the prophet's warning. Ultimately, it was his silence, indifference, and lack of action that sealed the tragic fate of his household [רלב״ג, רד״ק, מלבי״ם].