Musnad Ahmad 2:101

Yahya ibn Sa'id narrated to us, I asked him, Sulayman ibn al-Mughirah narrated to us, Thabit narrated to us, from Anas, who said: We were with Umar between Makkah and Madinah, and we looked for the crescent moon. I had sharp eyesight, so I saw it. I began saying to Umar: "Do you not see it?" He said: "I will see it while I am lying on my bed." Then he began to speak to us about the people of Badr. He said: "The Messenger of Allah, peace and blessings of Allah be upon him, used to show us the places where they would fall the day before. He would say: 'This is the place where so-and-so will fall tomorrow, if Allah wills, and this is the place where so-and-so will fall tomorrow, if Allah wills.'" He said: "And they began to fall exactly upon those spots." He said: "I said: 'By the One who sent you with the truth, they did not miss those spots; they fell exactly upon them.'" Then he ordered them to be thrown into a well. He went to them and said: "O so-and-so, O so-and-so, have you found what your Lord promised you to be true? For I have found what my Lord promised me to be true." Umar said: "O Messenger of Allah, are you speaking to a people who have become corpses?" He said: "You are not more hearing to what I say than they are, but they are unable to answer."