وَمَا عَلَيْكَ أَلَّا يَزَّكَّىٰ
Sentence structure
The negative nominal clause states that responsibility is not upon you. أَلَّا يَزَّكَّىٰ is the subordinated clause: that he does not purify himself.
Ayah summary
The Prophet ﷺ was not responsible if that person refused to reform himself.
وَمَا — And not
Grammar: وَ is resumptive. مَا is a non-governing negative particle.
عَلَيْكَ — upon you
Grammar: عَلَيْ is a preposition functioning as the linked complement. Attached كَ is a second-person masculine singular pronoun functioning as the genitive complement.
أَلَّا — that not
Grammar: أَلَّا is formed from masdari/subjunctive أَنْ and non-governing negative لَا.
يَزَّكَّىٰ — he purifies himself
Grammar: A form V third-person masculine singular imperfect verb in the subjunctive mood under أَنْ; لَا negates it without governing it. The complete clause is the complement of masdari أَنْ.