The Messenger of Allah ﷺ said, "Your lifespan compared to the lifespans of those who came before you is like the time between the afternoon prayer and sunset."
حدثنا مؤمل حدثنا سفيان عن عبد الله بن دينار سمعت
قال رسول الله ﷺ أجلكم في أجل من كان قبلكم كما بين صلاة العصر إلى غروب الشمس
Its isnad is sahih. Its origin is part of the beginning of hadith 5902 with this same isnad, but that part was not mentioned there, it was mentioned here alone. Bukhari related it, 9:59, from the report of Thawri from Ibn Dinar, in full, as we noted regarding his reports there. In all those places we referred to in Bukhari, the two hadiths were mentioned together, except in 6:361, where this hadith was not mentioned at the start of that one.As for his words, "concerning the lifespan of those before you," in one report of Bukhari it reads, "your remaining time compared to those who came before you." Hafiz said in Fath al-Bari, 2:32, its meaning is that the proportion of the duration of this nation to the duration of the nations that came before is like the proportion of the time between the Asr prayer and sunset to the rest of the day. It is as if he said, your remaining time in relation to what has passed, and so on. The upshot is that "fi" here carries the meaning of "ila," with the implied noun omitted, and it is an expression of proportion.