كتاب الفتن وأشراط الساعة
54
The Book of Tribulations and Portents of the Last Hour
(27)
Chapter: The Approach Of The Hour
(27)
باب قُرْبِ السَّاعَةِ
Sahih Muslim 2952

'A'isha reported that when the desert Arabs came to Allah's Messenger (ﷺ) they asked about the Last Hour as to when that would come. And he looked towards the youngest amongst them and said:

If he lives he would not grow very old that he would find your Last Hour coming to you (he would see you dying).
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ كَانَ الأَعْرَابُ إِذَا قَدِمُوا عَلَى رَسُولِ اللَّهِ صلى الله عليه وسلم سَأَلُوهُ عَنِ السَّاعَةِ مَتَى السَّاعَةُ فَنَظَرَ إِلَى أَحْدَثِ إِنْسَانٍ مِنْهُمْ فَقَالَ ‏ "‏ إِنْ يَعِشْ هَذَا لَمْ يُدْرِكْهُ الْهَرَمُ قَامَتْ عَلَيْكُمْ سَاعَتُكُمْ ‏"‏ ‏.‏
Reference : Sahih Muslim 2952
In-book reference : Book 54, Hadith 172
USC-MSA web (English) reference : Book 41, Hadith 7050
  (deprecated numbering scheme)