Q: What is the work of creation?
A: The work of creation is, God's making all things of nothing, by the word of his power, in the space of six days, and all very good.

Hebrews 11:3. Through faith we understand that the worlds were framed by the word of God, so that things which are seen were not made of things which do appear.
Revelation 4:11. Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created.
Genesis 1:1-31.

Westminster Project - For more info, see Thomas Boston's sermon on the Work of Creation.