What is the ruling on the authenticity of the hadith "Praise be to Allah for the blessing of Islam, and that is sufficient as a blessing," and what is its correct wording?

The statement mentioned is not a hadith, as it is not found in the books of hadith. There is no harm in saying it as a good statement, but not as a hadith. It is preferable to modify the phrasing to: "Praise be to Allah for the blessing of Islam, and what a magnificent blessing it is." Islam is the most excellent of blessings, and it is the origin of all goodness and happiness in this world and the Hereafter, as indicated by the verse: {This day I have perfected for you your religion and completed My favor upon you and have approved for you Islam as religion} [Al-Ma'idah: 3]. Ibn Kathir interpreted this to mean that the completion of the religion is the greatest of Allah's favors upon the Ummah.