Nahj al-Balāgha
Hadith 1588وَحَاشَ لِلَّهِ أَنْ تَلِيَ لِلْمُسْلِمِينَ بَعْدِي صَدْراً أَوْ وِرْداً، أَوْ أُجْرِيَ لَكَ عَلَى أَحَدٍ مِنْهُمْ عَقْداً أَوْ عَهْداً!!
May Allāh forbid that you be in charge of people's affairs after my assuming authority as Caliph, or that I issue an edict or document granting you authority over any one of them.