What is meant by the earth "before it was flattened" in the saying of Ibn Abbas and Ibn Kathir, and is it permissible to adopt the view of Qatadah and Al-Qurtubi regarding the creation of the heavens first, and were the heavens and earth created from primordial water, and is the Big Bang theory compatible with the Qur'an?

Allah created the earth before the heaven, then He spread the earth after creating the heaven, and the substance from which the heaven was created is water vapor. The "Big Bang" theory does not, in principle, contradict what Islam has affirmed regarding the beginning of creation, but it is merely an explanatory theory and not a basis for the people of faith concerning the existence of the Lord and His creation.