Explanation of the Hadith: Seven whom Allah will shade on a day when there is no shade except for his shade

Short piece from the back of the book:

On that day, there will be no device to seek shade from; nor any place to find refuge; nor any trees, tents, or homes for people to find protection from the heat of the sun. Rather on that day, all of the people will be exposed to the sun. And there will be nothing between them and the sun. No shade will be given except for those whom Allah honors with his shade on the great day.