What is the ruling on saying, "The mind of the Most Merciful has returned to him"?

There is nothing prohibited in the phrase "his mind returned to him by the mercy of the Most Merciful." The apparent and readily understood meaning is that attributing the mind to the Most Merciful is an attribution of creation and sustenance. The categories of what Allah has attributed to Himself are three: an entity existing by itself (created), an entity by which another exists (created), and a pure description in which the attributed is an attribute of Allah (uncreated). Accordingly, attributing the mind to Allah falls into the second category, meaning the sound mind, upright upon the creation of the Most Merciful.