From the mouth

God gave the ten commandments to Moses. This implies that God is communicating ideas that are to be understood in human terms. God said His creation took six days and not six billions years old. This agrees with Genesis chapter one because the Bible supports the Bible. This should settle the length of the days of creation.
It was not man that stated the heavens and earth were created in six days but God on stone tablets.

Exodus 20:11

 For in six days the Lord made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy.

 

 

Exodus 31:17-18

 

¹⁷ It will be a sign between me and the Israelites forever, for in six days the Lord made the heavens and the earth, and on the seventh day he rested and was refreshed.’”
¹⁸ When the Lord finished speaking to Moses on Mount Sinai, he gave him the two tablets of the covenant law, the tablets of stone inscribed by the finger of God.