The Messenger of Allah ﷺ said, "Whoever supports a dispute unjustly, or aids in oppression, remains under the wrath of Allah until he desists."
حدثنا محمد بن ثعلبة بن سواء حدثني عمي محمد بن سواء عن حسين المعلم عن مطر الوراق عن نافع
قال رسول الله ﷺ من أعان على خصومة بظلم أو يعين على ظلم لم يزل في سخط الله حتى ينزع
No references are available.
[Its isnad is hasan] Abu Dawud narrated it in the Book of Judgments, chapter on a man who assists in a dispute without knowing its details, hadith no. 3598, from the hadith of Matar, through him.