What is the ruling on congratulating people on the arrival of the month of Ramadan with phrases such as "Kul 'am wa antum bi-khair" (May you be well every year), or "Ramadan Kareem" (Generous Ramadan), or "Mubarak ash-shahr 'alaykum" (May the month be blessed for you)? And is there a specific wording mentioned in the Sunnah?

The Prophet, peace and blessings be upon him, used to gladden his Companions with the advent of Ramadan (definition). Imam Ahmad narrated from Abu Hurairah that the Prophet said: "Ramadan has come to you, a blessed month. Allah has obligated its fasting upon you. In it, the gates of Paradise are opened, the gates of Hellfire are closed, and the devils are chained. In it is a night better than a thousand months. Whoever is deprived of its goodness is indeed deprived." Some scholars considered this hadith (definition) a basis for congratulating people on the arrival of the month, and the matter in this regard is broad.