What is the ruling on a researcher saying that the creation of the heavens and the earth in six days does not refer to the days as we know them, and does this contradict the Prophetic Hadith that specifies the creation of everything on a particular day?

Allah created the heavens and the earth in six days, as mentioned in multiple Quranic verses, such as His saying: "And He it is Who created the heavens and the earth in six days" (Hud: 7).

The details of this are that the earth was created in two days, and its provisions were determined and the firm mountains were placed in it in another two days, making the total four days. Then, the seven heavens were created in another two days, bringing the total creation of the heavens and the earth to six days. Scholars explain that the mention of four days in His saying: "in four days" (Fussilat: 10) is a completion of the first two days, meaning within a total of four days.

As for the nature of these days, many exegetes have concluded that they are not like our known days. They could be days from the days of the Hereafter, where each day is a thousand years, or they could be long astronomical periods and cycles, or phases that the creatures went through, as our days are a temporal measure specific to the Earth after its creation. The true knowledge of their nature is with Allah Almighty.

Regarding the narrated hadith about the creation of soil, mountains, trees, light, and animals in seven days, scholars have differed on its authenticity. Some have weakened it, considering it to be from the words of Ka'b al-Ahbar, while others have authenticated it, seeing no contradiction with the Quran. The Quran speaks about the creation of the heavens and the earth in six days, whereas the hadith speaks about the creation of what is on the earth, and that these seven days could be days like ours, while the six days mentioned in the Quran could be longer.