In our study of Genesis chapter seven, we look at the first rain upon the earth and the flood of judgment that it brought. In chapter six, we saw how God made preparations for this day of judgment by preserving a remnant of mankind as well as the animals of the earth.
"The Lord then said to Noah, 'Go into the ark, you and your whole family, because I have found you righteous in this generation.'" NIV translation
All the preparations have been made and now comes the time of decision. God instructs Noah to take his family and enter the ark. There, they would be saved from the judgment that is to come through the waters. This is a picture of the salvation that was to come through Jesus Christ. This verse has caused some confusion and false teaching because of the fact that Noah's family was allowed to enter the ark because of him. There are many who think that they can ride another person's faith and enter heaven through them but that is not what happened with Noah's family. Noah would have explained to them what God said was going to happen and, at that point, they had the chance to either believe God (by faith) or to reject it and stay outside the ark and perish.
"'Take with you seven of every kind of clean animal, a male and its mate, and two of every kind of unclean animal, a male and its mate, and also seven of every kind of bird, male and female, to keep their various kinds alive throughout the earth.'" NIV translation
God instructed Noah to take seven pairs of clean animals and birds into the ark with him. This was God's way of providing for the sacrifices that are to come. He also had Noah take two pairs of unclean animals to repopulate the earth.
"'Seven days from now I will send rain on the earth for forty days and forty nights, and I will wipe from the face of the earth every living creature I have made.'" NIV translation
Why did God wait seven days? Throughout the Bible, the number seven is associated with completion and here we see that God gives everyone the chance to repent. During these seven days, others could have accepted the word of God by faith and been saved but they did not. He gave them every (complete) opportunity to repent. God explains to Noah that it is going to rain for forty days and nights and we are reminded that the number is associated with complete earthly trouble/testing.