Musnad Ahmad 27:1678

Ya'qub narrated to us, my father narrated to us, from Salih, Nafi' narrated to us, that Abdullah ibn Umar said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The people of Paradise will enter Paradise." Abdullah ibn Ahmad said: My father said: And Sa'd narrated it to us, saying: "Allah will cause the people of Paradise to enter Paradise, and the people of the Fire to enter the Fire. Then a caller will stand between them and say: 'O people of Paradise, no death! And O people of the Fire, no death! Everyone is eternal in that which he is in.'"