Al-Dhahabi reported: Al-Fudayl ibn ‘Iyad, may Allah have mercy on him, said, “If I had one supplication to be answered, I would make it for no one but the ruler. If the ruler is righteous, it will lead to the righteousness of the country and the people.”
Source: Siyar A’lām al-Nubalā 8/434
عن الذهبي قال الفضيل رحمه الله لَوْ أَنَّ لِي دَعْوَةً مُسْتَجَابَةً مَا جَعَلْتُهَا إِلَّا فِي إِمَامٍ فَصَلَاحُ الْإِمَامِ صَلَاحُ الْبِلَادِ وَالْعِبَادِ
8/434 سير أعلام النبلاء