Tafsir of Ta-Ha 20:56

{We showed him Our signs...}

{We showed him}: We made him see them, or we made him recognize their validity and certainty. He only denied them out of his own injustice, just as the Almighty said: {And they denied them, while their souls were certain of them, out of injustice and arrogance} (al-Naml: 14), and as the Almighty said: {You have known that none has sent these down except the Lord of the heavens and the earth as evidence} (al-Isrāʾ: 102).

Regarding the Almighty’s saying {all of them, so he denied}, there are two interpretations:

1. The first: That this possessive definition (the pronoun "them") follows the same pattern as the definition by the definite article (al-), as if one were to say "all the signs." This means it only provides a definition of reference, pointing to the known signs—the nine signs specific to Moses (peace be upon him): the staff, the hand, the parting of the sea, the rock, the locusts, the lice, the frogs, the blood, and the raising of the mountain.
2. The second: That Moses showed him his signs and enumerated for him the signs and miracles granted to other prophets. Since he is a truthful prophet, there is no difference between what he reports and what is witnessed directly. Thus, he denied them all, and {refused} to accept any of them.

It is also said: He denied the signs and refused to accept the truth.

{He said: "Have you come to us to drive us out of our land with your magic, O Moses?"}