Ali on Forgiveness: If he lied about me, may Allah forgive him

Sufyan reported: A man came to Ali ibn al-Husyan, may Allah be pleased with him, and he said to him, “Indeed, a man has harmed and disparaged you!” Ali said, “Come to him with us.” They departed with him and he saw that he would stand up for himself, so when they came to the man, Ali said, “O you! If what you said is true, then may Allah forgive me. If what you said is false, then may Allah forgive you.”

Source: Ṣifat al-Ṣafwah 1/354

وعن سفيان قال جاء رجل إلى علي بن الحسين رضي الله عنه فقال له إن فلاناً قد آذاكَ ووقع فيك قال فانطلق بنا إليه فانطلق معه وهو يرى أنه سينتصر لنفسه فلما أتاه قال يا هذا إن كان ما قلتَ في حقاً فغفر الله لي وإن كان ما قلت في باطلاً فغفر الله لك

1/354 صفة الصفوة