‘Ali bin Abi Talhah reported that Ibn ‘Abbas commented on Allah’s statement, {a [Thu'ban] serpent, manifest}, refers to “The male snake.” As-Suddi and Ad-Dahhak said similarly. A report from Ibn ‘Abbas said, "{Then (Musa) threw his staff}, and it turned into a huge snake that opened its mouth and rushed towards Fir'awn. When Fir'awn saw the snake rushing towards him, he jumped from his throne and cried to Musa for help, so that Musa would remove the snake from his way. Musa did that.” As-Suddi commented, {and behold! It was a [Thu'ban] serpent, manifest!} “This [Thu'ban] refers to male snakes. The snake opened its mouth and headed towards Fir'awn to swallow him, placing its lower jaw on the ground and its upper jaw reaching the (top of the) wall of the palace. When Fir'awn saw the snake, he was frightened, so he jumped and wet himself and he never wet himself before this incident. He cried, ‘O Musa! Take it away and I will believe in you and release the Children of Israel to you.’ So Musa, peace be on him, took it, and it became a staff again."
{And he drew out his hand, and behold! it was white (with radiance) for the beholders.}

Musa took his hand out of his cloak after he inserted his hand in it and it was shining, not because of leprosy or sickness. Allah said in another Ayah, {[And put your hand into your bosom, it will come forth white without hurt.]}(quran/27/12) Ibn ‘Abbas said, “without hurt', means, 'not because of leprosy'. Musa inserted his hand again in his sleeve and it returned back to its normal color.” Mujahid and several others said similarly.