Throwing three handfuls of dust over the dead person's head

Q 3: Some people say that it is permissible for those who attend the funeral procession to participate in burying the dead person, even by throwing three handfuls of dust over the dead person's head . What is the ruling on that?

A 3: It is permissible for those who attend a funeral to participate in burying the dead person and to throw three handfuls of dust in the direction of their head. The Prophet (peace be upon him) offered the Janazah (funeral) Prayer then he went to the grave and stood at the head of the deceased and took three handfuls of dust and threw them into the grave. (Related by Ibn Majah). Moreover, `Amir ibn Rabi`ah narrated that the Prophet (peace be upon him) offered the Janazah Prayer over `Uthman ibn Mazh`un then he made Takbir (saying: "Allahu Akbar [Allah is the Greatest]") for him four times and went to his grave and threw three handfuls of dust while standing at his head. (Related by Al-Daraqutny). This was also the practice of the Companions (may Allah be pleased with them) as it was authentically reported from Ibn `Abbas (may Allah be pleased with him and his father) when he buried Zayd ibn Thabit that the former threw three handfuls of dust over the latter's grave and said: "Knowledge disappears this way." This was mentioned by Ibn Qudamah in his book Al-Mughny. (Part No. 7; Page No. 338)