What is the ruling on saying "I am grateful for such and such a thing"?

There is no harm in saying "I am grateful to so-and-so" in the sense of "I am thankful to him," for gratitude is the acknowledgment of a favor. However, the circulation of the term "gratitude" as a means to happiness and positive energy, and the dedication of courses and exercises to it, is an exaggeration that may lead to charlatanism and deception. Thanking someone who has done a favor is done by giving a gift, or a reward, or assistance, or by supplicating for them with good, such as saying "May Allah reward you with good," as reported from the Prophet, peace and blessings be upon him.