What is the wisdom behind mentioning "the heavens" in the plural form in Surat Al Imran and "the heaven" in the singular form in Surat Al Hadid when describing the vastness of Paradise, and what is the extent of validity that Arabs used the expression "the vastness of the heavens and the earth" to denote the greatness of something, and did they know of the existence of more than one heaven?

There are two interpretations for the noble verse "and a Garden whose width is the heavens and the earth." The first is that the intended meaning is the actual width, with an indication of its length. The second is a statement about the vastness of Paradise without specifying its length or width. Some scholars have mentioned that the mention of "heavens" (السماوات) in the plural in Surah Aal 'Imran, as opposed to "heaven" (السماء) in the singular in Surah Al-Hadid, is meant to exaggerate the encouragement for Jihad in Aal 'Imran. The word "heaven" in the verse from Al-Hadid refers to the genus of heaven, to encompass all heavens. The Arabs knew the heavens and the earth in ancient times and did not object to the mention of "heavens" in the plural in the Qur'an.