Garments of Skin (Light - )
Garments of skin (katnot 'ohr) our Sages differ on what this means. For some, they are garments made of the skin of animals. For others, they are garments for the skin, covering the skin but not the soul of man.
Rabbi Yehudah teaches that before the sin, man was enveloped in a halo of light. He appeared in a majestic splendor before all the creatures of heaven and earth. The Psalmist is referring to this sublime appearance when he exclaims, "Yet You have made him but slightly less than the angels, and crowned him with soul and splendor" (Tehillim 8:6). But, after the sin, the halo of glory which illuminated man's spirit disappeared; man was left only with "the garment which covers his skin."
And this is also how to understand the Midrash Bereishit Rabbah 20, which states, "The sefer Torah of Rabbi Meir has katnot ohr, garments of light, instead of garments of skin, the two words 'ohr (skin) and ohr (light) being homonyms."
According to RaMBaM this version refers to the time before the sin, when man was bathed in light.
Rabbi Yitzchak adds that the covering of the human body before the sin was made of the matter which forms fingernails. Man's body then was radiant with the brilliant whiteness of the moon at the base of the nail; he was admired by all creatures. After the sin, he was deprived of this natural shield. Only a trace of its original brilliance remains at the moons of his nails (Zohar 2:208b). This trace of the enchanting ideal of a lost paradise is in our thoughts at the close of the Shabbat, as we say the Havdalah prayer. During this prayer, we gaze at the moons of our fingernails as though to express the longing to keep a trace of the radiant Shabbat during the week to come.
After G-d had expelled man from Gan Eden He placed the Keruvim, i.e. angels (according to Rashi based on Shemot Rabbah 9,10) in the direction of the Tree of Life. The purpose of this was to create a barrier between the Tree of Life and man.
It is a well known fact that lahat (flame) is something intangible, but it is an attribute of cherev (sword) something very tangible indeed. The combination of the two is something which inspires great fear. Everyone who looks at the spectable is reminded forecefully of death when he beholds this spectacle. G-d's intention was to create an atmosphere which would discourage the pursuit of the Tree of Life and the attainment by man of an infinite life span on earth. G-d did not want His decree that man would be rehabilitated only through the death of his body to become null and void.
Another way of understanding the word keruvim is that it symbolizes the seven angels who preside over the various compartments of Gehinnom (Hades). The word keruvim is in the plural and the minimal plural is two. The extra letter heh in front equals 5 so that 2+5=7. Based on such an approach, the entire verse may be explained as follows: "The angels who have been placed in charge of Gehinnom, the fiery regions where the wicked keep turning themselves over like meat on a spit." Our Sages have explained this in similar terms i.e. that the word "lahat" is another word for Gehinnom, the place where justice is meted out to man after death. The word appears in that sense in Malachi 3:19.
We have a tradition that both the angels and Gehinnom were created on the second day. On the other hand, the Gan Eden on earth was created on the third day. Although man has been created later, he possesses the potential to defeat the forces that were created on the second day through his observance of the Torah's mitzvot. When that is the case, there is no barrier between man and the Tree of Life. On the contrary, then he may approach the Tree of Life and live forever.
We also learn from this verse, especially the words, et ha-keruvim, that these angesl are the ones we refer to in our prayers as Chayot HaKodesh. The names of these angels are mentioned in Yechezkel 10:20, "This is the Chayah which I have seen... and I realized that they are the Keruvim." It is a fact familiar to Kabbalists that every Chayah has 16 facets, four in each direction of the globe, as it is written in Yechezkel 1:6 "one of them had four faces (facets)." Seeing the word fanim consists of the singular "an, the rest is merely a plural ending. Hence four times fan in four directions each time totals 16. These keruvim are something intangible which flashes from the sword which seems in constant motion, turning over and over. This is what is meant by the words ve'et lahat hacherev hamithapechet, i.e. G-d's angel Chayah, the one with 16 facets. This angel symbolizes His Attribute of Justice. You must understnad how it is possible that this angel is called lahat, suggesting it is a great power, whereas according to our verse here this lahat appears as something subordinate, an adjective, something "carried" by the sword. This is always the case with the angels called Chayot HaKodesh.
The Ineffable Name of G-d which represents the pinnacle of all intelligence are alluded to here, i.e. the highest of the ten emanations is represented by the letter yud at the beginning of G-d's Name and the remaining letters heh-vav-heh corresponds in their numerical value (16) to the 16 facets of the Chayot HaKodesh. The Torah which is called Etz HaChayim (the Tree of Life), has been given to us by means of 16 covenants, 13 of them are mentioned in connection with the ritual of circumcision, whereas the word brit (covenant) appears three more times in connection with the Torah's report of the revelation at Har Sinai where we received the Torah.
Sign Upon Kayin
On Kayin's forehead G-d inscribed a letter of the Divine Name.
The Sages of the Midrash quote differing opinions on the nature of this sign, depending on whether they consider Kayin to be a repentant sinner or not. Some mention that G-d had Kayin protected by a dog who guided him and fought off menacing beasts. Others explain that Kayin himself became a warning sign to murderers, or the herald of encouragement for the penitent.
And others say that the sign was leprosy, since he was leprous, the animals recognized him, and would not come close to him (Ibid. Cf. Zera Berakh, Part 1).
Another opinion states the murder occurred on the eve of the Shabbat at twilight. The merit of the Shabbat then protected Kayin, safeguarding him from all evil. According to this, the "sign" that G-d gave Kayin was the Shabbat, which is often referred to as a "sign."
Whatever the sign was, G-d did this because Kayin confessed that he had sinned. He wanted to give sinners a chance, so they would not think that once a person sins, there is no longer any help for him. One must realize that if he repents completely, he is no longer subject to the punishments mentioned in the Torah.
Even though Kayin confessed, he did not repent completely. G-d therefore decreed that vengeance be extracted against him after seven generations.
Land of Nod
Kayin then went to the land of Nod, which means "wandering; be moving, to rove." This was to the East of Eden, it was the same place Adam had gone to when he was driven from the Garden. The same was also true later of all accidental murderers. They must suffer the penalty of exile, and the refuge cities where they must stay are to the east of the Holy Land (BaMidbar 35:11; Devarim 4:41).
The Talmud seems to suggest that Nod is a proper noun and interprets this verse as follows: "Kayin lived in (that is, settled in) the land of Nod."
The Talmud concludes, "This teaches that a fugitive's life in exile atones for half of his sins - since Kayin was allowed to settle in Nod after his wandering" (Sanhedrin 37b)
Call of the Torah, by Rabbi Elie Munk
Torah Commentary, by Rabbi Bachya ben Asher
Yalkut MeAm Loez [Torah Anthology], Rabbi Yaakov Culi, Book One - Beginnings