The Messenger of Allah ﷺ said, "Cursed is the one who has intercourse with his wife in her anus."
حدثنا وكيع حدثنا سفيان عن سهيل بن أبي صالح عن الحارث بن مخلد
قال رسول الله ﷺ ملعون من أتى امرأته في دبرها
Its isnad is hasan. Harith bin Mukhallad, Ibn Hajar said of him that he is majhul al-hal (of unknown status), and Ibn Hibban mentioned him in al-Thiqat, and they were silent about him. The hadith is found in Abu Dawud, 2/249, no. 2162.