The Prophet ﷺ said, "Most of the punishment of the grave is due to urine."
حدثنا عفان حدثنا أبو عوانة عن سليمان الأعمش عن أبي صالح
عن النبي ﷺ قال أكثر عذاب القبر في البول
Its isnad is sahih. Hakim narrated it in 1/183, in the chapter on purification, on most punishment of the grave being due to urine, Ibn Majah in the chapter on purification, on being strict about urine, 1/125 no. 348, Ibn Abu Shayba in 1/122, in the chapter on purification, on guarding against urine, and Daraqutni in 1/128.