Seth (Hebrew: שֵׁת, Standard Šet, Tiberian Šēṯ; Arabic: شيث Shith or Shiyth; "Placed; appointed"), in the Book of Genesis of the Hebrew Bible, is the third listed son of Adam and Eve and brother of Cain and Abel and is the only other son mentioned by name. According to Genesis 4:25, Seth was born after the slaying of Abel by Cain, and Eve believed God had appointed him as "replacement" for Abel "because Cain killed him". He is commemorated as one of the Holy Forefathers in the Calendar of Saints of the Armenian Apostolic Church on July 30.
Seth in the Hebrew Bible
In Genesis, Seth was the third son of Adam and Eve, and is their only child mentioned by name besides Cain and Abel. After stating that Seth was to Adam "a son in his likeness and image", born when Adam was 130 years old (Genesis 5:3), Genesis 5:4 states that Adam fathered "sons and daughters" before his death aged 930 years.
Seth had a son, Enosh, or Enos at age 105 (Genesis 5:6) and further children; he lived 912 years (Genesis 5:8).
Rashi (Rabbi Shlomo Yitzhaqi) refers to Seth as the ancestor of Noah and hence the father of all mankind. According to Zohar 1:36b, Seth is "ancestor of all the Generations of the Tzaddikim" (righteous ones). Parshat Balak refers to "all of Seth's descendants" (Numbers 24:17).
Seth in Gnosticism
In Gnosticism, Seth is seen as a replacement given by God for Cain and Abel. It is said that late in life, Adam gave Seth secret teachings that would become the Kabbalah.
One particular school of Gnosticism arose which focused on Seth called the Sethians.
Josephus about Seth
Josephus refers to Seth as the most notable of the sons of Adam in the Antiquities of the Jews, and reports that his descendants built the Pillars of the sons of Seth.
Seth in the Garden of Eden
According to the noncanonical Testament of Adam and medieval legend, Adam, knowing his death is near, calls his son Seth to his side. He tells Seth to go back to the Garden of Eden, to enter and get three seeds from the fruit of the Tree of Life. Adam then instructs Seth to return to him and place the three seeds in his mouth before burying his body. Seth does as his father requests and makes the trip to the Garden of Eden. At the gate stands the Archangel Michael, who asks Seth his business. Seth tells him, and Michael lets him pass, directing him to the tree of life. Seth collects three seeds from the fruit of the tree, and then returns, back through the gates, down to his father, who by this time has died. He digs Adam's grave, and buries him, placing the three seeds in his mouth before covering him with dirt. Eventually three trees spring up from Adam's grave, and it is these three trees that are later chopped down to provide the wood for the three crosses on Golgotha.