The Messenger of Allah ﷺ said, "Most of the punishment of the grave comes from urine."
قال رسول الله ﷺ أكثر عذاب القبر من البول.
Ibn Majah (348) narrated it from Abu Bakr bin Abu Shayba, and it is also in his Musannaf (1/122), where he said, Affan told us, he said Abu Awana told us, from Amash, from Abu Salih, from Abu Hurairah, and he related the hadith.Daraqutni also narrated it (1/128) and said, Sahih. And Hakim narrated it (1/183) and said, Sahih according to the standard of the two Shaykhs (Bukhari and Muslim), and I do not know of any defect in it.Busiri mentioned it in Zawaid bin Majah and said, This isnad is sahih, its narrators to the very last one are relied upon in the Sahihayn.Tirmidhi related in his Ilal, on the authority of Bukhari, that he said it is a sahih hadith. As for Abu Hatim, he said it is a false hadith, meaning as a raised (marfu) narration, Ilal (1/366).I say, this is an example of the difference in the scholars' assessments.