The Prophet ﷺ passed by two graves and said, "These two are being punished, and they are not being punished for something major. One of them is being punished for not being careful with urine, and the other is being punished for backbiting."
حدثنا أبو بكر بن أبي شيبة حدثنا وكيع حدثنا الأسود بن شيبان حدثني بحر بن مرار
مر النبي ﷺ بقبرين فقال إنهما ليعذبان وما يعذبان في كبير أما أحدهما فيعذب في البول وأما الآخر فيعذب في الغيبة
[Sahih] Ahmad narrated it (5/39) from Waki, with the same wording.Bakr heard this hadith from Abdul-Rahman bin Abu Bakra, from his father, Musnad Ahmad (5/35, 36), but he is accused of confusion in narration (ikhtilat), and it has not been established that he narrated it before his confusion set in, so the chain is daif. The hadith has many corroborating narrations, including the previous hadith, no. 347.