Dua When seeing someone Afflicted by Misfortune - Alhamdulillah illazi aafaanee....

The Messenger of Allah (may the peace and blessings of Allah be upon him) said: Whoever sees an afflicted person and says: 

الحَمْدُ لِلَّهِ الَّذِي عَافَانِي مِمَّا ابْتَلَاكَ بِهِ

وَفَضَّلَنِي عَلَى كَثِيرٍ مِمَّنْ خَلَقَ تَفْضِيلًا

Praise be to Allah who had saved me from 

what He had afflicted you with

and for honoring me over many of his creations

Tirmidhi 3431

Note:
The Prophet (may the peace and blessings of Allah be upon him) would say this du'a without letting the afflicted person hear him, as not to hurt him.