What is the ruling on repentance from mocking others, slandering them, and pleasing people at the expense of pleasing Allah?

This person has committed a grave sin by slandering and defaming Muslims. He must immediately initiate sincere repentance with its conditions: abandoning the sin, resolving not to return to it, and regretting his action.

He is obligated to seek forgiveness from those he wronged, according to most scholars. Some scholars hold that abundant supplication for them and mentioning their good qualities suffices.

If he repents with a sincere repentance that fulfills its conditions, then Allah will accept his repentance.