It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) came to the grave of Abdullah bin Ubayy after he had been placed in it. He (peace and blessings be upon him) gave the order and he was taken out; he (peace and blessings be upon him) placed him on his knees, applied his blessed saliva to him, and clothed him in his shirt. And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6685