التفسير التبليغي
(And his companion will say, "This is what is with me, prepared.") (50:23)
Mujahid said: This is the speech of the driving angel, who says: This is the son of Adam whom You entrusted me with; I have brought him forth.
(And his companion will say,) Muqatil said: He is his angel who used to record his evil deeds in the worldly life.
(This is what is with me, prepared.): Meaning, this is something fixed and prepared with me.
(prepared): Meaning, present and not absent, recording whatever he says, whether good or evil.
Source: التفسير التبليغي