Allah, The Glorious, tests the followers of the prophets to distinguish between the sincere from the insincere. Allah(SWT) made the Prophet Noah (AS) marry a woman who turned to be disobedient then from the people of hellfire, same was the wife of Prophet Lut (AS). Allah (SWT) aims to examine the faith of people who claim being followers of the Prophet (SAWA) as we read in Quran:
1. (Allah will not leave the believers in the state in which you are now until He distinguish the bad from the good). Sura Aal Imran, verse 179.
2. (In order that Allah may distinguish the bad persons from the good persons ) Sura Al-Anfaal, verse 37.
Having a disobedient wife among good wives and insincere companion among sincere companions makes the bad persons follow the bad, while sincere persons keep on following the Prophet (SAWA) and his successors.