What is the ruling on saying: "May Allah accept from us by the secrets of Surat Al-Fatiha" after supplication?

This supplication is permissible because it is a tawassul (seeking nearness to Allah) through the Quran, which is allowed because the Quran is the word of Allah and one of His attributes. Tawassul through the attributes of Allah is legislated. And Al-Fatihah is the essence of the Quran, as it was narrated from Al-Hasan Al-Basri that the essence of all books is gathered in Al-Fatihah, and the essence of Al-Fatihah is in His saying, the Most High: "It is You we worship and You we ask for help."