The Prophet ﷺ said, "The gates of heaven are opened every Monday and Thursday, and on that day every servant who associates nothing with Allah is forgiven, except a man who harbors a grudge against his brother. Concerning them it is said, 'Leave these two until they reconcile.'"
وبهذا الإسناد عن النبي ﷺ قال تفتح أبواب السماء كل يوم اثنين وخميس فيغفر ذلك اليوم لكل عبد لا يشرك بالله شيئا إلا امرأ كان بينه وبين أخيه شحناء فيقال أنظروا هذين حتى يصطلحا
Its chain of transmission is sahih. It has occurred previously at 7093, and it is found in Muslim with similar wording, 4/1987, no. 2565, in the Book of Righteousness, the prohibition of indecency, and in Abu Dawud, 4/279, no. 4916, and Tirmidhi, 4/373, no. 2023, in the Book of Righteousness, what has been said about those who forsake one another, where he said, hasan sahih, and in Malik, 2/908, in good character, what has been said about forsaking one another, and in Abdul-Razzaq, 10/169, no. 20226.