Preparing food for the family of the deceased

It is narrated from al-Ahnaf bin Qays (may Allah have mercy on him) that I used to hear Sayyiduna Umar (may Allah be pleased with him) say: "No person of Quraysh enters any door (or affair) except that other people certainly enter it along with him." Al-Ahnaf said: I did not understand the real meaning of these words of his, until, when Sayyiduna Umar (may Allah be pleased with him) was stabbed, he ordered Sayyiduna Suhayb (may Allah be pleased with him) to lead the people in prayer for three days, and also instructed that food be arranged for the people. So when the people returned, having finished with the funeral, the dining cloths had already been spread, but the people held back from the food because of the deep grief and sorrow that had come upon them. Then Sayyiduna al-Abbas bin Abd al-Muttalib (may Allah be pleased with him) came and called out: "O people, (Umar) has indeed passed away" (to the end of the hadith).
This narration, if Allah Almighty wills, will come later in full detail in the section on the virtues of Sayyiduna Umar (may Allah be pleased with him).

It is narrated from Sufyan (may Allah have mercy on him) that Tawus (may Allah have mercy on him) said: "The dead are put to trial in their graves for seven days; that is why the early generations (Salaf) liked to feed people on their behalf during those days."
Imam Ahmad (may Allah have mercy on him) recorded it in Kitab al-Zuhd.