I envy no one, nor am I partial to anyone. I am equal to all. But whoever renders service unto Me in devotion is a friend, is in Me, and I am also a friend to him. The Supreme Lord has no enemy or friend, but He is inclined toward a devotee who always engages in His devotional service. Similarly, elsewhere in the Gita (16.19) the Lord says:

Those who are envious and mischievous, who are the lowest among men, are cast by Me into the ocean of material existence, into various demoniac species of life. The Lord is extremely antagonistic toward those who are envious of His devotees. To protect His devotees, the Lord sometimes has to kill their enemies. For example, to protect Prahlada Maharaja, the Lord had to kill his enemy Hiranyakasipu, although Hiranyakasipu attained salvation because of being killed by the Lord. Since the Lord is the witness of everyones activities, He witnesses the actions of the enemies of His devotees, and He is inclined to punish them. In other cases, however, He simply witnesses what the living entities do and gives the results of ones sinful or pious actions.