Sahih al-Bukhari, Volume 5, Book 58, Hadith 136 (USC-MSA) ⓘ
Narrated Usaid bin Hudair: A man from the Ansar said, "O Allah's Messenger! Will you appoint me as you have appointed so-andso?" 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).
حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا غُنْدَرٌ، حَدَّثَنَا شُعْبَةُ، قَالَ سَمِعْتُ قَتَادَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، عَنْ أُسَيْدِ بْنِ حُضَيْرٍ، أَنَّ رَجُلاً، مِنَ الأَنْصَارِ قَالَ يَا رَسُولَ اللَّهِ، أَلاَ تَسْتَعْمِلُنِي كَمَا اسْتَعْمَلْتَ فُلاَنًا قَالَ " سَتَلْقَوْنَ بَعْدِي أَثَرَةً فَاصْبِرُوا حَتَّى تَلْقَوْنِي عَلَى الْحَوْضِ " .
also referenced under: Book 63, Hadith 18 (In-Book) & Hadith 3792 (DarusSalam)