Is saying "May God have mercy on him" or "May God heal him," and the like, considered a command from a human being to God Almighty?

Phrases such as "the deceased so-and-so" (al-marhum fulan) are correct and permissible. They constitute a supplication and a request from the servant to God for mercy or healing. In an authentic hadith, the Prophet, peace and blessings be upon him, said about 'Amir ibn al-Akwa': "May Allah have mercy on him" (yarhamuhu Allah). This is equivalent to "O Allah, have mercy on him." There is no difference between saying "al-marhum" (the deceased) or "so-and-so, may Allah have mercy on him," for both are valid for conveying news and for supplication, depending on the intention of the speaker, and what is meant by them is hope, optimism, and prayer.