18 But I will establish My covenant with you; and you shall go into the ark—you, your sons, your wife, and your sons’ wives with you.
19 And of every living thing of all flesh you shall bring two of every sort into the ark, to keep them alive with you; they shall be male and female.
20 Of the birds after their kind, of animals after their kind, and of every creeping thing of the earth after its kind, two of every kind will come to you to keep them alive.
21 And you shall take for yourself of all food that is eaten, and you shall gather it to yourself; and it shall be food for you and for them.”
22 Thus Noah did; according to all that God commanded him, so he did.
In Genesis 7:2, God commanded seven of each of the clean beasts that were suitable for sacrifice.
covenant (v.18) — first use of the word in Scripture. The details of covenant are given in Genesis 9:9-17 when Noah leaves the ark.
Morris makes the point that larger animals on the ark were probably young ones that hadn’t yet reached full growth. In addition, many (if not all) the animals may have hibernated while on the ark.
Noah was not only a man of strong faith in God’s word, but of thoroughgoing obedience to that word. the tasks God had given him to do were monumental—extremely difficult and discouraging—and yet Noah never questioned or complained. He simply obeyed!
This last verse of the sixth chapter succinctly summarizes a whole century of God’s “long-suffering” while Noah “preached righteousness” to those “who were disobedient while the ark was a preparing” (1 Peter 3:20; 2 Peter 2:6; Luke 17:26-27).
Not only in this verse, but three times more we are told that Noah did all God commanded him (Genesis 7:5, 9, 16). … Because Noah walked with God and was obedient in faith to His word, God had wonderful fellowship with Noah. There are seven recorded instances in which it is said that God spoke to Noah (Genesis 6:13; 7:1); 8:15; 9:1, 8, 12, 17), each time in fellowship and blessing to Noah and his family. — Morris, page 187.
It is clear from the perspective of the text itself that [the flood] is to be regarded as a world-wide event. In the present passage this is underscored by the three-fold occurrence of the expression “all flesh” (Genesis 6:13, 17, and 19), which occurs 33 times elsewhere in the Hebrew Bible and clearly refers to all living creatures, both human and animal (cf., e.g., Job 34:15; Jeremiah 25:31; Ezekiel 21:5). The universal scope of the Flood is further emphasized by the later reference to the water covering “all the high mountains everywhere under the heavens” (Genesis 7:19) as well as God’s promise to “never again destroy every living thing” with a Flood (Genesis 8:21).
God’s concern for animal life—though secondarily, as always, with respect to human life—is borne out by His statement to Noah in vs. 19-20 concerning their preservation by boarding the ark in representative pairs of male and female. This statement is intended to inform Noah of the content of the ark, not as a directive for him to find and assemble these pairs himself—which would be a quite impractical, if not impossible human feat, even assuming Noah had comprehensive knowledge of every class or genus of animal on land, Hence, quite consistently, God concludes by informing Noah that these animal pairs shalle come to him of their own accord (viz., by God’s leading). — Wechsler, pages 139-140
The especial significance of the statement that “Noah did according to all that God commanded him”—which is repeated again in 7:5—becomes evident when once considers that Noah in fact says nothing throughout the entire course of the Flood narrative proper (what he does say in 9:25-27 is many years after the Flood). Indeed, Noah is the only major figure involved in an extended biblical event to whom no words are attributed in the course of that event—the point being that his obedience was expressed by his action. In the New Testament this point is further driven home—and, even more so, applied to evangelism—by Peter’s reference to Noah as a “preacher of righteousness” (2 Peter 2:5)—and yet he never said a word! The writer of Hebrews likewise emphasizes the evangelistic ministry of Noah as extending from his actions when he writes that “in reverence [Noah] prepared the ark … by which he condemned the world” (Hebrews 11:7). … This emphasis on the evangelistic aspect of active obedience is likewise evident in the third and last epistolary reference to Noah in the New Testament, in 1 Peter 3:18-20, in which the Apostle points out that it was the “Spirit” of Christ in Noah—that is, the Holy Spirit—that enabled Noah (just as He enables every believer in any age) to obey God and build the ark, and in so doing to “preach (the need for repentance)” to the people of his time, who nonetheless rejected Noah’s message and remain in prison (i.e., hell) until the day of final judgment (cf. Revelation 20:13-14). — Wechsler, pages 141-142.