Hawzah News Agency – Imam Ali peace be upon him says:

أيُّها النّاسُ، سَلُوا اللَّهَ اليَقينَ، وارغَبوا إلَيهِ في العافِيَةِ؛ فإنّ أجَلَّ النِّعمَةِ العافِيَةُ، وخَيرُ مادامَ في القَلبِ اليَقينُ، والمَغبونُ مَن غُبِنَ دِينَهُ، والمَغبوطُ مَن غُبِطَ يَقينَهُ .

'O people! Ask Allah for conviction and seek good health from him, for the greatest of blessings is good health and the best thing that can reside in the heart is conviction. A cheated man is he who has been cheated of his religion and an enviable person is he whose conviction is envied.'

Source: Bihar al-Anwar, v. 70, p. 176, no. 33