The Messenger of Allah ﷺ said, "I will go ahead of you to the Pool, and I will boast of your numbers before the other nations, so do not kill one another after me."
حدثنا محمد بن عبد الله بن نمير حدثنا أبي ومحمد بن بشر قالا حدثنا إسمعيل عن قيس
قال رسول الله ﷺ ألا إني فرطكم على الحوض وإني مكاثر بكم الأمم فلا تقتلن بعدي
[Its isnad is sahih]. It was narrated by Humaydi, no. 351, and Ahmad, 4/349, and others, through various routes from Ismail bin Abu Khalid, with this wording, and he made clear that he heard it directly in the version of Ahmad. Mujalid also narrated it in agreement with him. The hadith has many corroborating narrations, and Busiri graded the hadith of Ibn Majah as sahih.