What is the difference between rancor (hiqd), envy (hasad), the evil eye (al-'ayn), and praiseworthy emulation (ghibṭah), and which of them are permissible and which are forbidden?

Enmity is intense malice, while envy is wishing for the cessation of blessings upon others, and both are forbidden. As for coveting, it is wishing to attain a blessing similar to one possessed by another, and it is permissible. It may be metaphorically called envy, as mentioned in the Hadith: "There is no envy except in two [cases]."