Tafsir of Abasa 80:7

"And it is not upon you that he might not purify himself." That is, there is no harm upon you if he does not purify himself through Islam, such that your eagerness for his conversion should compel you to turn away from the one who has already embraced Islam.

"Ma" (in ma ‘alayka) is a negation, and the sentence is a circumstantial state (hal) pertaining to the pronoun in "he approached" (tasadda). In reality, that which is forbidden is turning away from the one who has embraced Islam, not the act of addressing the other or concerning oneself with his affairs out of eagerness for his conversion.

It is also possible that "ma" is interrogative, used for the purpose of denunciation; meaning: "What harm is there upon you if he does not purify himself?" The outcome of this, too, is negation.