Is saying "May your religion be pleased" unlawful in Sharia?

Preserving the tongue is one of the greatest acts that draw one closer to Allah. A servant must guard against every word from which no benefit or advantage for their religion is expected; otherwise, they should refrain from uttering it. The tongue can either demolish a servant's good deeds or their sins, and from this stems the importance of controlling one's speech.

The phrase "may your religion be pleased" (يسعد دينك) in common usage means to supplicate for the person's happiness and that their religion be a source thereof, or to supplicate for the religion itself with victory and strength. Both meanings are legitimate supplications for good for a Muslim, and there is no harm in them.