Nasai

(1) "One hundred years": In all the preceding narrations, seventy years is mentioned. It appears that neither of these numbers is intended as a specific figure; rather, abundance is meant—that is, He will remove it far away. In common usage, the numbers seventy and one hundred are generally used to indicate a large quantity. The reason for specifying these two numbers could be that the average human lifespan is generally around seventy years, and very few reach or exceed one hundred years. Some scholars have also said that it is possible that the reward was less at first, then Allah Ta'ala, out of His grace, increased it; this is not far-fetched either.

(2) In the narrations above, the year is referred to as "khareef" (autumn), because there is only one autumn season in a year, so it makes no difference. The reason for specifying this season is that, in Arabia, it was the time for crops and fruits to ripen, be harvested, and picked; therefore, before the adoption of the Hijri calendar, Arabs used to refer to dates in terms of the autumn season.