He came to the Prophet ﷺ and said, "Abu Talib has died."The Prophet ﷺ told him, "Go and bury him."He said, "He died as a polytheist."The Prophet ﷺ replied, "Go and bury him."He said, "After I buried him, I returned to the Prophet ﷺ, and he told me, 'Perform a full bath.'"
حدثنا محمد بن جعفر حدثنا شعبة عن أبي إسحاق قال سمعت ناجية بن كعب يحدث
أنه أتى النبي ﷺ فقال إن أبا طالب مات فقال له النبي ﷺ اذهب فواره فقال إنه مات مشركا فقال اذهب فواره قال فلما واريته رجعت إلى النبي ﷺ فقال لي اغتسل
Its isnad is sahih. Najiyah bin Kaab is al-Asadi, a trustworthy Kufan successor. Bukhari gave him a biographical entry in al-Kabir 4/2/107 and mentioned no criticism of him. Some have confused him with Najiyah bin Khaffaf, Abu Khaffaf al-Anazi, the narrator from Ammar bin Yasir, but they are definitely two different people. Bukhari distinguished between them in al-Kabir, giving each a separate entry, and Muslim and Abu Hatim also distinguished between them, as al-Hafiz established in al-Tahdhib.The hadith was narrated by Abu Dawud (3:206) and Nasai (1:282-283). It will come at greater length as no. 1093, and see also 807 and 1074.