Reference : Hisn al-Muslim 128

حَسْبُـنا اللهُ وَنِعْـمَ الوَكـيل
Ḥasbunallāhu wa ni`mal-wakīl.

Allah is sufficient for us and the best of those on whom to depend.

Reference:
Al-Bukhari, 5/172.

Chapter: Upon encountering an enemy or those of authority