It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Your Lord Almighty has said: When I take away something dear from My servant (such as his eyesight), and he is grieved over it, then he praises Me for it, I will not be pleased with any reward for him other than Paradise."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7473