I also asked this here, but I think it fits better in Biblical Hermeneutics after thinking about it.
Genesis 4:23-24 (NIV)
23 Lamech said to his wives, “Adah and Zillah, listen to me; wives of Lamech, hear my words. I have killed a man for wounding me, a young man for injuring me. 24 If Cain is avenged seven times, then Lamech seventy-seven times. ”
Who did Lamech kill and why is this even important?
While we do not know the identity of the man killed, we see here Lamech's (perverted) idea of justice.
From the NET Bible
sn Seventy-seven times. Lamech seems to reason this way: If Cain, a murderer, is to be avenged seven times (see v. 15), then how much more one who has been unjustly wronged! Lamech misses the point of God’s merciful treatment of Cain. God was not establishing a principle of justice when he warned he would avenge Cain’s murder. In fact he was trying to limit the shedding of blood, something Lamech wants to multiply instead. The use of “seventy-seven,” a multiple of seven, is hyperbolic, emphasizing the extreme severity of the vengeance envisioned by Lamech.
Lamech has taken two wives. In the verses just before, we see that people have learned to shape metal and some have become nomadic shepherds. We are seeing here the decline of human ethics/morality/justice even as their technology and skill increase.
Just to add to @Frank Luke answer, although the Bible didn't mention who Lamech killed, The book of Jashar, an aggadic text, does.
The book of Jashar identifies the person Lamech killed as Tubal Cain in Chapter 2, verses 26-35. Lamech had mistakenly killed Cain so his two wives Adah and Zillah planned to kill him hence the saying about 77 fold avenging of his own death.
While i do not consider the book of Jashar an authoritative book, I do believe that it sheds more light to understanding reasons why some things happened in the Bible. Having read it twice, I don't see anything contradictory to the Bible
PS: I couldn't update my comment so I had to post it as an answer
It seems likely that Lamech slew Enoch, who, compared with the length of the lives of his ancestors, was yet a young man. The generations match--both the sixth generation from Adam. Cain would have been a very old man by this time (somewhere around 900 years old).
The Lineage of Cain:
The lineage of Seth: (Year of birth (approx.), Name, Age at death)
Though there isn't sufficient information to be absolutely certain, the evidence fits.
I researched this issue in relation to another question and found some interesting data in rabbinical sources:
The Midrash Tanchuma (Bereshit 11:2-4) identifies Lamech's (accidental) victims as his ancestor Cain and his own son.
Cain became an angel of death, wandering and roaming about, accursed. Lamech, his descendant in the seventh generation, who was blind, would go hunting led about by his young son... One time the lad said to his father: “I see some kind of beast in the distance.” Lamech sent his arrow in that direction, and Cain was slain. As they approached the corpse, the lad... said to his father: “The corpse resembles a man.” Thereupon, Lamech cried out: “Woe is me, it is my grandfather.” In his grief, he clasped his hands together, and accidentally struck the child’s head, killing him…
Above: Cover page of a 1522 edition of Midrash Tanchuma published in Constantinople.
This tradition basically agrees with the information provided by the Book of Jasher as mentioned by @Taiwo Kareem in this thread. However the Book of Jasher is not ancient. Also called Pseudo-Jasher, it is an 18th century fiction pretending to be one of the Bible's lost books. The Midrash Tanchuma predates Pseudo Jasher by about a millennium. Thus the tradition preserved by Jasher almost certainly originates in the Midrash Tanchuma.
It is not an admission rather a threat.
I have killed - הָרַ֙גְתִּי֙ - a man for wounding me, a young man for injuring me.
Genesis 4:23 NIV
The AKJV has a marginal reference for "have killed" being "would kill".
"I would certainly have killed - הָרַ֖גְתִּי - you by now ..."
Numbers 22:33
Further :
“Adah and Zillah, listen to me; wives of Lamech, hear my words.
If Cain is avenged seven times, then Lamech seventy-seven times.”
Genesis 4:23-24 NIV
Enoch, the seventh from Adam, prophesied about them: “... all the defiant words ungodly sinners have spoken against him.” These people ... boast about themselves and flatter others for their own advantage.
Jude verses 14-16 NIV
Enoch, seventh from Adam via Seth - Genesis 5
Lamech, seventh from Adam via Cain - Genesis 4:16-18
Lamech is boasting to his wives of his intent to kill any male for any slight.
The deliberate encompassing nature of the boast precludes it from being an act, rather a threat.
More than that, he is threatening to take matters into his own hands regarding the exile of Cain :
Cain said to the Lord, “My punishment is more than I can bear."
Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth ...
Genesis 4:13-14 NIV
If a seven-fold vengeance would be inflicted for the death of Cain in isolation, a seventy-seven-fold vengeance would be inflicted by the annihilation of the line of Seth, who were still in "the land", and still in fellowship or "walking with" elohim, and that would require death of father or son or both.
It's hyperbole.
This is why Enoch was moved out of harm's way by elohim :
By faith, Enoch was translated, so as not to see death, and was not found, because that, God, had translated him ...
Hebrews 11:5 Rotherham
Translated - μεταθέσεως - indicates a geographical move.
Used in Acts 7:16 referencing the movement of human remains from Egypt to Shechem.
And of course Hebrews informs us that as expected Enoch died, only not by Lamech's hand :
All these people were still living by faith when they died. They did not receive the things promised; they only saw them and welcomed them from a distance, admitting that they were foreigners and strangers on earth.
Hebrews 11:13 NIV
This geographical movement to avoid death is recorded in the Genesis account of Enoch :
When Enoch had lived 65 years, he became the father of Methuselah.
After he became the father of Methuselah, Enoch walked - וַיִּתְהַלֵּ֨ךְ - faithfully with God 300 years and had other sons and daughters.
Altogether, Enoch lived a total of 365 years.
Genesis 5:21-23 NIV
Elohim - god - also walked or 'fellowshipped' with Adam and Eve in the garden :
Then the man and his wife heard the sound of the Lord God as he was walking - מִתְהַלֵּ֥ךְ - in the garden in the cool of the day ...
Genesis 3:8 NIV
Enoch produces the next heir in the line of Seth :
When Enoch had lived 65 years, he became the father of Methuselah.
Genesis 5:21 NIV
Then he is translated or moved out of harms way so that he should not die at the hand of Lamech :
After he became the father of Methuselah, Enoch walked faithfully with God 300 years and had other sons and daughters.
Genesis 5:21-23 NIV
Then his age at death :
Altogether, Enoch lived a total of 365 years.
Genesis 5:21-23 NIV
This translation at 65 and walking with elohim for a further 300 years, is given in summary as the notable feature of his life :
... and Enoch walked with God,––and was not, for God had taken him.
Genesis 5:24 Rotherham
This was not and walked with god in Genesis being equivalent to the was not found and translation occuring in Hebrews.
Cheers.
