وَإِنَّهُ عَلَىٰ ذَٰلِكَ لَشَهِيدٌ
And indeed he is a witness to that. (100:7)
Two well-attested analyses identify the pronoun -hu differently. On one, the human being bears witness to his own ingratitude through evident conduct or recognition. On another, God is the witness, making divine scrutiny and warning especially prominent.
Inna and the lām of la-shahīd reinforce the assertion in either reading. The disagreement concerns which antecedent the pronoun refers to, not a defect in the wording. One should identify the interpretive alternative and then discuss the effect it produces.