حَسْبِـيَ اللهُ وَنِـعْمَ الوَكيـل
Hasbiyal-lah waniAAmal-wakeel
Translation
Allah is sufficient for me, and how fine a trustee He is.
When to recite
Recited when a matter overtakes you or when you feel overwhelmed.
Source / Reference
Al-Bukhari 5/172