Sahih al-Bukhari — Merits of the Helpers in Madinah (Ansaar) — Hadith No: 3801
Translation
Narrated Anas bin Malik:The Prophet (ﷺ) said, "The Ansar are my near companions to whom I confided my private secrets, People will go on increasing but the Ansar will go on decreasing; so accept the good of the good-doers amongst them and excuse the wrong-doers amongst them