It is reported that Al-Ḥasan Al-Baṣrī – Allāh have mercy on him – said:

People will remain upon good as long as they vary (some are more knowledgeable, righteous etc); when they become equal, that is when they are destroyed.

Al-Bayhaqī, Shuʿab Al-Īmān #8664 (Al-Rushd ed.).