Nahj al-Balāgha

ومن كتاب له (عليه السلام) إلى معاوية في أول ما بويع له، ذكره الواقدي في كتاب الجمل

To Mu‘āwiyah, soon after Amīr al-mu’minīn was sworn in. (Muḥammad ibn ‘Umar) al-Wāqidī has mentioned this in his “Kitāb al-Jamal”

مِنْ عَبْدِ اللهِ عَلِيٍّ أَمِيرِ الْمُؤْمِنِينَ إِلَى مُعَاوِيَةَ بْنِ أَبِي سُفْيَانَ:

From the servant of Allāh, ‘Alī Amīr al-mu’minīn to Mu‘āwiyah son of Abū Sufyān :

أَمَّا بَعْدُ، فَقَدْ عَلِمْتَ إِعْذَارِي فِيكُمْ، وَإِعْرَاضِي عَنْكُمْ، حَتَّى كَانَ مَا لَا بُدَّ مِنْهُ وَلَا دَفْعَ لَهُ، وَالْحَدِيثُ طَوِيلٌ، وَالْكَلَامُ كَثِيرٌ، وَقَدْ أَدْبَرَ مَا أَدْبَرَ، وَأَقْبَلَ مَا أَقْبَلَ، فَبَايِعْ مَنْ قِبَلَكَ، وَأَقْبِلْ إِلَيَّ فِي وَفْدٍ مِنْ أَصْحَابِكَ، وَالسَّلَامُ.

Now, you are aware of my excuses before you people and my shunning you till that happened which was inevitable and which could not be prevented. The story is long and much is to be said. What was to pass has passed and what was to come has come. Therefore, secure (my) allegiance from those who are with you and come in a deputation of your people to me; and that is an end to the matter.