What is the Shariah ruling on supplicating with: "O Allah, grant us the permanence and perfection of Your Oneness (Tawhid), and the permanence and perfection of servitude to You alone, and the permanence and perfection of disbelief in anything besides You, and in ourselves"? And how can a beneficial book be authored for the Ummah and marketed?

There is nothing that indicates impropriety in the statement: "O Allah, grant us the permanence and perfection of Your Oneness, and the permanence and perfection of servitude to You alone," and "the permanence and perfection of disbelief in all that is besides You" if it refers to disbelief in what is worshipped other than Allah, and "the permanence and perfection of disbelief in ourselves" if it refers to not seeing any merit in oneself.

It is recommended to adhere to the supplications and remembrances that are authentically reported in the Qur'an and Sunnah (definition).

It is encouraged to author beneficial books from which people can benefit, due to the great good and reward therein, in accordance with the saying of the Prophet, peace and blessings be upon him: "When a person dies, all his deeds come to an end except for three: ongoing charity, or knowledge from which people benefit, or a righteous child who prays for him."

As for how to author and market a book, one should refer to specialists.