To understand the background, you’ve got to read this story first: Moosa and Khadir.
Narrated Said bin Jubair:
I said to Ibn ‘Abbas, “Nauf-Al-Bakali claims that Moses (the companion of Khadir) was not the Moses of Bani Israel but he was another Moses.” Ibn ‘Abbas remarked that the enemy of Allah (Nauf) was a liar.
Note: Ibn Abbas said this in a state of anger without intending to abuse Nauf but to affirm that he did not tell the truth (see Fath Al-Bari, Vol. I, P.229)
But let’s just take his reaction in consideration here. He rendered Nauf the enemy of Allah because he lied. Whether Nauf did that intentionally or unintentionally is not under discussion here.
Lesson: The liar is Allah’s enemy. O_O