It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him): "Whoever washes the deceased should take a ritual bath (ghusl), and whoever lowers him into his grave should perform ablution (wudu)." And a statement of the same meaning has been reported from Ibn al-Musayyib (may Allah have mercy on him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1449