Jibreel despised Firaun. He hated him so much that he kicked dirt in his mouth as he was dying, such was his wish to prevent Firaun from repenting.
Because this is how merciful our Lord is; that the greatest tyrant the world has ever known would have been granted forgiveness had he asked for it.
However, Jibreel wasn’t so forgiving. Such was his love for Allah, Jibreel could not forgive the claims Firaun made.