From Sahih Bukhari (Hadith 6683):
Narrated `Abdullah:Allah's Messenger (ﷺ) said a sentence and I said another. He said, "Whoever dies while he is setting up rivals along with Allah (i.e. worshipping others along with Allah) shall be admitted into the (Hell) Fire." And I said the other: "Whoever dies while he is not setting up rivals along with Allah (i.e. worshipping none except Allah) shall be admitted into Paradise
Reference: Bukhari 6683