The wickedness of the world, which provoked God's wrath and caused the flood, 1-7. Noah finds grace, 8. His generations, etc., 9-13. The order, form, dimensions, and end of the ark, 14-22.
1 And it came to pass, when men began to multiply on the face of the earth and daughters were born to them, 2 That the sons of God saw the daughters of men that they were fair. And they took for themselves wives from all whom they chose. 3 And the LORD said, "My Spirit shall not always strive with man, because he is flesh; therefore, his days shall be one hundred and twenty years." 4 There were Nephilim in the earth in those days, and also after that, when the sons of God came in to the daughters of men and they bore children to them. The same became mighty men who were of old, men of renown.
5 And GOD saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually. 6 And the LORD repented that he had made man on the earth, and it grieved him in his heart. 7 And the LORD said, "I will destroy man whom I have created from the face of the earth—man, beast, the creeping animal, and the birds of the air. For I repent that I have made them." 8 But Noah found grace in the eyes of the LORD.
9 These are the generations of Noah. Noah was a just man and perfect in his generations, and Noah walked with God. 10 And Noah begot three sons: Shem, Ham, and Japheth.
11 The earth was also corrupt before God. And the earth was filled with violence. 12 And God looked upon the earth, and behold, it was corrupt, for all flesh had corrupted his way upon the earth.
13 And God said to Noah, "The end of all flesh has come before me, for the earth is filled with violence through them. Behold, I will destroy them with the earth. 14 Make yourself an ark of gopher-wood. You shall make rooms in the ark and shall pitch it inside and outside with pitch. 15 And this is the fashion in which you shall make it: the length of the ark shall be three hundred cubits, its breadth fifty cubits, and its height thirty cubits. 16 You shall make a window for the ark, and you shall finish it to a cubit upward. And the door of the ark you shall set in its side. With lower, second, and third stories you shall make it. 17 And behold, I, even I bring a flood of waters upon the earth to destroy all flesh, in which is the breath of life, from under heaven. And everything that is on the earth shall die. 18 But with you I will establish my covenant. And you shall come into the ark—you, your sons, your wife, and your sons' wives with you. 19 And of every living thing of all flesh, two of every sort you shall bring into the ark to keep them alive with you. They shall be male and female. 20 Of birds after their kind, of cattle after their kind, and of every creeping animal of the earth after its kind, two of every sort shall come to you to keep them alive. 21 And take for yourself from all food that is eaten, and you shall gather it to yourself, and it shall be for food for you and for them." 22 And Noah did so. According to all that God commanded him, so he did.
Matthew Henry Commentary - Genesis, Chapter 6[➚]
[v.4] - "There were Nephilim in the earth in those days" - LXX: "Now the giants were upon the earth in those days..." The KJV also uses the word "giants" in place of Nephilim. Concerning these "giants," Matthew Poole says this: "Giants; men so called, partly from their high stature, but principally for their great strength and force, whereby they oppressed and tyrannized over others: for this is mentioned as another sin, and cause of the flood; and therefore they seem to be here noted, not for the height of their stature, which is no crime, but for their violence, which also is expressed beneath, Genesis 6:11, Genesis 6:13." From the Keil and Delitzsch Biblical Commentary on the Old Testament: "Luther gives the correct meaning, 'tyrants:' they were called Nephilim because they fell upon the people and oppressed them... The meaning of the verse is a subject of dispute. To an unprejudiced mind, the words, as they stand, represent the Nephilim, who were on the earth in those days, as existing before the sons of God began to marry the daughters of men, and clearly distinguish them from the fruits of these marriages."