﴿ وَمَا يُدْرِيكَ لَعَلَّهُۥ يَزَّكَّىٰٓ ﴾

“Yet for all thou didst know, [O Muhammad,] he might perhaps have grown in purity,”

And how would you know? Perhaps he would cleanse himself yazzakkā the original tā’ of yatazakkā has been assimilated with the zāy that is perhaps he would purge himself of sins by what he hears from you