בראשית, פרק ה׳, פסוק ח׳

The early records of humanity trace a direct historical line connecting Adam to Noah, documenting the remarkably long lives of these ancient ancestors. As this family tree unfolds, the specific sons named to carry on the legacy are not necessarily the firstborns. A particular son might be highlighted because his birth acts as a major turning point, splitting his father's life into two distinct eras: the years before fatherhood and the years that follow. There may also be other unique reasons for singling out a specific child. Ultimately, the chosen son stands out because he forms the crucial link in the continuous family chain that eventually leads to Noah [ביאור שטיינזלץ].

Seth's total lifespan reached nine hundred and twelve years. The twelve years added to his base life of nine hundred can be understood by breaking them down into two distinct periods: a block of five years, which equals sixty months, and another block of seven years [קאסוטו].