Narrated Ibn `Abbas:

'Allah is Sufficient for us and He Is the Best Disposer of affairs," was said by Abraham when he was thrown into the fire; and it was said by Muhammad when they (i.e. hypocrites) said, "A great army is gathering against you, therefore, fear them," but it only increased their faith and they said: "Allah is Sufficient for us, and He is the Best Disposer (of affairs, for us)." (3.173)

حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ ـ أُرَاهُ قَالَ ـ حَدَّثَنَا أَبُو بَكْرٍ، عَنْ أَبِي حَصِينٍ، عَنْ أَبِي الضُّحَى، عَنِ ابْنِ عَبَّاسٍ، ‏{‏حَسْبُنَا اللَّهُ وَنِعْمَ الْوَكِيلُ‏}‏ قَالَهَا إِبْرَاهِيمُ عَلَيْهِ السَّلاَمُ حِينَ أُلْقِيَ فِي النَّارِ، وَقَالَهَا مُحَمَّدٌ صلى الله عليه وسلم حِينَ قَالُوا ‏{‏إِنَّ النَّاسَ قَدْ جَمَعُوا لَكُمْ فَاخْشَوْهُمْ فَزَادَهُمْ إِيمَانًا وَقَالُوا حَسْبُنَا اللَّهُ وَنِعْمَ الْوَكِيلُ‏}
USC-MSA web (English) reference : Vol. 6, Book 60, Hadith 86
Arabic reference : Book 65, Hadith 4563