Sahih Bukhari
Merits of the Helpers in Madinah (Ansaar)
Volume: 005 / Book Number: 058 / Hadith Number: 136
Narrated Usaid bin Hudair:
A man from the Ansar said, "O Allah's Apostle! Will you appoint me as you have appointed so-and-so?" The Prophet said, "After me you will see others given preference to you; so be patient till you meet me at the Tank (i.e. Lake of Kauthar). (on the Day of Resurrection)."