Language:
كتاب الرقاق
81  
To make the Heart Tender (Ar-Riqaq)
(42)
Chapter: The stupors of death
(42)
باب سَكَرَاتِ الْمَوْتِ
Sahih al-Bukhari 6511

Narrated `Aisha:

Some rough bedouins used to visit the Prophet (ﷺ) and ask him, "When will the Hour be?" He would look at the youngest of all of them and say, "If this should live till he is very old, your Hour (the death of the people addressed) will take place." Hisham said that he meant (by the Hour), their death.

حَدَّثَنِي صَدَقَةُ، أَخْبَرَنَا عَبْدَةُ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رِجَالٌ مِنَ الأَعْرَابِ جُفَاةً يَأْتُونَ النَّبِيَّ صلى الله عليه وسلم فَيَسْأَلُونَهُ مَتَى السَّاعَةُ، فَكَانَ يَنْظُرُ إِلَى أَصْغَرِهِمْ فَيَقُولُ ‏ "‏ إِنْ يَعِشْ هَذَا لاَ يُدْرِكْهُ الْهَرَمُ حَتَّى تَقُومَ عَلَيْكُمْ سَاعَتُكُمْ ‏"‏‏.‏ قَالَ هِشَامٌ يَعْنِي مَوْتَهُمْ‏.‏
Reference : Sahih al-Bukhari 6511
In-book reference : Book 81, Hadith 100
USC-MSA web (English) reference : Vol. 8, Book 76, Hadith 518
  (deprecated numbering scheme)