Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) came to the graveyard and said: "'As-salamu alaykum dara qawmin mu'minin, wa inna in sha' Allahu bikum lahiqun, wadidtu anna qad ra'ayna ikhwanana' (Peace be upon you, O dwellers of the abode of the believers! If Allah wills, we shall surely join you. I wish that we could see our brothers.)" The people said: Are we not your brothers? He (peace and blessings be upon him) said: "Rather, you are my Companions; my brothers are those who will come later." They said: O Messenger of Allah, how will you recognise those of your Ummah who will come later? He (peace and blessings be upon him) said: "What do you think: if a man had horses with white foreheads and white legs among horses that are pitch black, would he not recognise his horses?" They said: Certainly, O Messenger of Allah! He (peace and blessings be upon him) said: "The people of my Ummah too will come with radiant faces and limbs from ablution, and I will be their forerunner at the Pool. Beware! People will be driven away from my Pool just as a stray camel is driven away. I will call out to them: 'Come here!' Then it will be said: 'They changed the religion after you.' Then I will say: 'Suhqan suhqan' (Away with them, away with them!)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 7209