حَسْبِـيَ اللّهُ وَنِعْـمَ الوَكِيل
Hasbiyal-lahu waniAAmal-wakeel
Translation
Allah is sufficient for me and He is the best Guardian.
When to recite
Recited when afraid or overwhelmed. This was said by Ibrahim (AS) when thrown in the fire.
Source / Reference
Al-Bukhari 5/172