When did God make or bring into existence the seas on the surface of the Earth?

Allah created the heavens and the earth in six days. He created the earth in two days, then He created the heavens in two days, then He flattened the earth in another two days by bringing forth from it its water and its pasture. Thus, the flattening of the earth and the gushing forth of its seas and rivers occurred in the last two days of the days of creation. This is the most preponderant view in reconciling the verses, and it is the opinion of Ibn Abbas, which Ibn Jarir preferred.