Bismillah ArRahman ArRaheem
Wa-Alaykum As Salaam
That particular statement is not an Ayah of the Holy Qur'an. The closest there is with regards to a reference to seven Heavens is as follows:
قُلْ مَن رَّبُّ السَّمَاوَاتِ السَّبْعِ وَرَبُّ الْعَرْشِ الْعَظِيمِ 23:86
Say: Who is Lord of the seven heavens, and Lord of the Tremendous Throne?
تُسَبِّحُ لَهُ السَّمَاوَاتُ السَّبْعُ وَالْأَرْضُ وَمَن فِيهِنَّ ۚ وَإِن مِّن شَيْءٍ إِلَّا يُسَبِّحُ بِحَمْدِهِ وَلَـٰكِن لَّا تَفْقَهُونَ تَسْبِيحَهُمْ ۗ إِنَّهُ كَانَ حَلِيمًا غَفُورًا 17:44
The seven heavens and the earth and all that is therein praise Him, and there is not a thing but hymneth His praise; but ye understand not their praise. Lo! He is ever Clement, Forgiving.
Otherwise, what you are after is a supplication, for which you can find the translation of it in the Islamic Laws book of Syed Sistani under the title Translation "Obligatory acts relating to Namaz » Translation of prayers" here = https://www.sistani.org/english/book/48/2232/
And is pasted here for your convenience, with the relevant part in bold:
IV. Translation of Qunut
La ilaha illallahul Halimul Karim (There is none worth worshipping but Allah Who is Forbearing and Generous).
La ilaha illallahul 'Aliyyul 'Azim (There is none worth worshipping but Allah Who is Eminent and Great).
Subhanallahi Rabbis samawatis sab' wa Rabbil arazinas sab' (Glory be to Allah, Who is the Sustainer of the seven heavens and of the seven earth).
Wama fi hinna wama bayna hunna, wa Rabbil 'arshil 'azim (And Who is the Sustainer of all the things in them, and between them, and Who is the Lord of the great 'Arsh (Divine Power).
Wal hamdu lillahi Rabbil Aalamin (And all praise for Allah, the Sustainer of the worlds).