Is the aforementioned narration regarding the virtue of the Ummah of Muhammad (peace be upon him) and the virtue of the five daily prayers and fasting, which is attributed to the book "Tanbih al-Ghafilin" by Abu al-Layth al-Samarqandi, authentic?

The book "Tanbih al-Ghafilin" is full of fabricated hadiths that have no basis, and what is quoted in the question from it is fabricated, as it shows clear signs of being objectionable and contrived. It is not permissible to attribute it to the Prophet, may Allah bless him and grant him peace. And whoever insists on attributing it to him while knowing its falsity has committed a grave sin, because the Prophet, may Allah bless him and grant him peace, said: "Whoever narrates a hadith (definition) from me, and he sees that it is a lie, then he is one of the liars."