The dead is punished because of the lamentation of the living.

May Allah have mercy upon Abu 'Abd al-Rahman (the kunya of Ibn 'Umar) that he heard something but could not retain it (well). (The fact is) that the bier of a Jew passed before the Messenger of Allah (ﷺ) and (the members of his family) were waiting over him. Upon this he said: You are wailing and he is being punished.

He (Ibn 'Umar) missed (the point). The Messenger of Allah (ﷺ) had (in fact) said: He (the dead) is punished for his faults or for his sins, and the members of his family are wailing for him now. (This misunderstanding of Ibn 'Umar is similar to his saying: ) The Messenger of Allah (ﷺ) stood by the well in which were lying the dead bodies of those polytheists who had been killed on the Day of Badr, and he said to them what he had to say, i. e.: They hear what I say. But he (Ibn 'Umar) misunderstood. The Prophet (ﷺ) had only said: They (the dead) understand that what I used to say to them was truth. She then recited: Certainly, thou canst not make the dead hear the call (xxvii. 80), nor can you make those hear who are in the graves, nor can you inform them when they have taken their seats in Hell.

I heard the Messenger of Allah (ﷺ) saying: He who is lamented upon would be punished because of the lamentation for him on the Day of judgment.