وَمَا عَلَيْكَ أَلَّا يَزَّكَّىٰ
Though it is not your concern if he should not grow (in fulness).
Though you are not accountable if he does not grow in purity (through acceptance of faith and fulfilling its obligations and responsibilities).
Though you are not to blame if he does not purify himself.
although thou art not accountable for his failure to attain to purity; 3
Whereas it is not on thee that he is not cleansed.
And you have nothing to lose if he does not become pure.
Yet no blame is on you if he grow not (spiritually).
And it (is) not on you that he not purifies/corrects (himself).
you will not be held responsible if he would not purify himself.
And as to him who comes to thee striving hard,
though you will not be questioned even if he never purifies himself.
Yet it is not thy concern if he grow not (in grace).
And no blame is on you if he would not purify himself
What does it matter to you if he will not become pure (from disbelief, you are only a Messenger, your duty is to convey the Message of Allah).
Though it is no blame to thee if he grow not (in spiritual understanding).