Genesis 6 first gives Noah instructions to build the Ark. Genesis 6:14–16 describes the vessel’s material, dimensions, compartments, roof, and side door.
The instructions follow Genesis’s account of widespread human violence and corruption. God announces a coming Flood and tells Noah to make the Ark for the preservation of his household and representatives of living creatures. The chapter therefore establishes both the reason for the vessel and its basic design.
Genesis 7 continues with the animals entering and the Flood beginning. Genesis 8 describes the waters receding and Noah leaving the Ark, while Genesis 9 records the covenant associated with the aftermath. The story spans several chapters rather than appearing in one isolated passage.
Readers sometimes answer Genesis 7 because that is where the Flood begins. That chapter gives further entry instructions and the event’s opening, but the original construction command appears earlier, in Genesis 6.