Musnad Ahmad 46:0

Narrated to us by Muhammad ibn Ja’far, who said: Narrated to us Shu’bah, from Isma’il ibn Umayyah, who said: I heard my grandfather say: I was sitting with the Messenger of Allah (ﷺ), and a man came to him and said: "O Messenger of Allah, what are the two things that make [Paradise or Hellfire] necessary?" He (ﷺ) said: "Whoever dies while associating nothing with Allah enters Paradise, and whoever dies while associating something with Allah enters the Fire."