(a) Sayyiduna Ibn Umar (may Allah be pleased with them both) said: No one should pray the funeral prayer except one who is in a state of purity.
(b) Imam Malik (may Allah have mercy on him) also narrated it this way from Nafi' (may Allah have mercy on him). What is reported from him (Ibn Umar) about tayammum for the funeral prayer may possibly have been on a journey when water was not available.
(c) In the chain of the hadith of Sayyiduna Ibn Umar (may Allah be pleased with them both) about tayammum there is weakness, which we have explained in Kitab al-Ma'rifah.
(d) The narration of al-Mughirah bin Ziyad, from Ata (may Allah have mercy on him), from Sayyiduna Ibn Abbas (may Allah be pleased with them both), is not authentically established from him; it is only the saying of Imam Ata (may Allah have mercy on him).
(e) Likewise Ibn Jurayj (may Allah have mercy on him) narrated it from Imam Ata (may Allah have mercy on him) as his own saying. This is one of the things for which Imam Ahmad bin Hanbal and Yahya bin Ma'in (may Allah have mercy on them both) criticised al-Mughirah bin Ziyad. It has also been narrated as a marfu' hadith of the Prophet (peace and blessings be upon him), and that is a mistake, which we have explained in al-Khilafiyyat.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1093