Sahih Muslim Book 31, Hadith Number 5885.
Ibn Abu Mulaika reported: I heard Ibn ‘Abbas as saying: When ‘Umar b. Khatab was placed in the coffin the people gathered around him. They praised him and supplicated for him before the bier was lifted up, and I was one amongst them. Nothing attracted my attention but a person who gripped my shoulder from behind. I saw towards him and found that he was ‘All. He invoked Allah’s mercy upon ‘Umar and said: You have left none behind you (whose) deeds (are so enviable) that I love to meet Allah with them. By Allah, I hoped that Allah would keep you and your two associates together. I had often heard Allah’s Messenger (may peace be upon him) as saying: I came and there came too Abu Bakr and ‘Umar; I entered and there entered too Abu Bakr and ‘Umar; I went out and there went out too Abu Bakr and ‘Umar, and I hope and think that Allah will keep you along with them.