Albert Barnes Commentary Genesis 7:1-9

"And Jehovah said unto Noah, Come thou and all thy house into the ark; for thee have I seen righteous before me in this generation. Of every clean beast thou shalt take to thee seven and seven, the male and his female; and of the beasts that are not clean two, the male and his female: of the birds also of the heavens, seven and seven, male and female, to keep seed alive upon the face of all the earth. For yet seven days, and I will cause it to rain upon the earth forty days and forty nights; and every living thing that I have made will I destroy from off the face of the ground. And Noah did according unto all that Jehovah commanded him. And Noah was six hundred years old when the flood of waters was upon the earth. And Noah went in, and his sons, and his wife, and his sons` wives with him, into the ark, because of the waters of the flood. Of clean beasts, and of beasts that are not clean, and of birds, and of everything that creepeth upon the ground, there went in two and two unto Noah into the ark, male and female, as God commanded Noah." — Genesis 7:1-9 (ASV)

1. טהור ṭâhôr “clean, fit for food or sacrifice.”
2. יקוּם yeqûm “standing thing; what grows up, whether animal or plant.” Compare קמה qāmâh “stalk, or standing corn.”

Here is found the command to enter the ark. The general direction in the preceding chapter was given many years ago, before the ark was commenced. Now, when it is completed, a more specific command is issued. For thee have I seen righteous before me. Noah has accepted the mercy of God, is therefore set right in point of law, and walks rightly in point of practice. The Lord recognizes this indication of an adopted and renewed son. “In this age” he and his were the solitary family so characterized. (Genesis 7:1–4)

Of all clean cattle. - Here the distinction of clean and unclean animals meets us without any previous notice. How it became known to Noah we are not informed. From the former direction it appears that the animals were to enter by pairs. Now it is further arranged that there are to be seven pairs of the clean cattle and fowl, and only one pair of the unclean. (Genesis 7:2–3)

Seven days after the issue of the command the rain is to commence, and continue for forty days and nights without ceasing. “Every standing thing” means every plant and animal on the land. (Genesis 7:4)

The execution of the command is recorded and fully particularized with the additional circumstance of the age of Noah. “The son of six hundred years,” in his six hundredth year. Went they unto Noah. They seem to have come under the influence of a special instinct, so that Noah did not require to gather them. Seven days were employed in receiving them, and storing provisions for them. (Genesis 7:5–9)