In response to a letter from Muawiya
Nahj al-Balāgha|Volume 1|Book 2|Chapter 17
فَلاَ تَجْعَلَنَّ لِلشَّيْطَانِ فِيكَ نَصِيباً، وَلَا عَلَى نَفْسِكَ سَبِيلاً، وَالسَّلَامُ.
Now, do not allow Satan have a share with you nor let him have his sway over you; and that is an end to the matter.