Which Tolkien work contains the creation account beginning with Eru Ilúvatar and the Ainur?

The Silmarillion contains Tolkien’s creation account beginning with Eru Ilúvatar and the Ainur.

Its opening section, the Ainulindalë, describes how Eru Ilúvatar creates the Ainur and brings the world into being through a great music. The account establishes the theological and musical foundations of Tolkien’s mythology.

The work was edited and published by Tolkien’s son Christopher in 1977, four years after Tolkien’s death. It brings together material about the creation of Arda, the wars against Morgoth, the history of the Elves, and later events involving Númenor.

Unlike The Hobbit and The Lord of the Rings, The Silmarillion is not a single continuous novel with one central hero. It is a collection of connected legends, histories, and tales from Tolkien’s larger fictional tradition.