Imam As-Sadiq (a.s.) said:
إنَّ الْمُؤْمِنَ أَشَدُّ مِنْ زُبُرِ الْحَدِيْدِ إنَّ زُبُرَ الْحَدِيْدِ إِذْا أُدْخِلَ النّارَ تَغَيَّرَ وَ إنَّ الْمُؤْمِنَ لَوْ قُتِلَ ثُمَّ نُشِرَ ثُمَّ قُتِلَ لَمْ يَتَغَيَّرْ قَلْبُهُ.
The believers are stronger than iron parts because when iron is exposed to fire, it changes, but if the believers are killed and then revived and again killed, there would be no change in their mentalities.1
Life is a series of problems and complicated matters. Weak people surrender to them very soon and escape from the field, whereas those who are strong on account of their belief stand firm to tackle the challenges.
They know that there will always be hindrances in complying with God’s command, abstaining from sin, and achieving honors and credits. They realize that self-control, self-sacrifice and resistance against rebellious desires is required in order to succeed. True belief gives them immense strength to continue their endeavor fearlessly in the path of religion.