How authentic are the two hadiths: "And know that you will not draw closer to Allah with anything greater than what came from Him," and "There is no prayer for one who does not recite the Opening of the Book and three verses after it"?

The Hadith (definition): "Allah has not permitted for a servant anything better than two rak'ahs he prays, and indeed, righteousness is showered upon the servant's head as long as he is in his prayer, and servants have not drawn closer to Allah with anything like that which came from Him – meaning the Qur'an" has a weak chain of narration. However, the phrase: "and servants have not drawn closer to Allah with anything like that which came from Him" is sound in meaning. The intention is that the Qur'an is revealed and uncreated, from Him it began and to Him it returns, meaning that Allah Almighty is its Speaker, and reciting the Qur'an is the best of remembrances.

As for the Hadith: "There is no prayer for one who does not recite Fatihat al-Kitab and three verses after it," it has not been found with this wording. Rather, it was narrated with the wording: "Nothing suffices in an obligatory prayer except Fatihat al-Kitab and three verses or more," which is a rejected narration. It was also narrated as a statement attributed to Uthman ibn Abi al-As with the wording: "No prayer is complete except with Fatihat al-Kitab and three verses or more."