Rashi lived before the era of Grammatical textbooks. Hence
one of his functions was to teach the rules of grammatical conjugation
similar to modern textbooks.
A fundamental principle in all languages is agreement. Subjects and
verbs must agree in gender and plurality.
Sometimes langauge achieve special effects by violating subject-verb agreement.
For example, using a feminine gender with a masculine subject could hint at helplessness.
Today we use the rule that a plural subject using a single verb indicates that
the first mentioned subject instigated the action and the others followed along.
Verse Gn09-23a discussing how two of Noach's children covered
his nakedness while drunk states
And Shem and Japheth [he] took a garment, and laid it upon both their shoulders, and went backward, and covered the nakedness of their father; and their faces were backward, and they saw not their father's nakedness.
Rashi commenting on the plural subject and single verb states:
Shem was the more religious one and instigated the action of covering up
their naked father. Yefet was interested in beauty and didn't particularly care
if Noach was naked but followed along when Shem asked him to help out.
The underlined phrases seem to suggest that men and women are separate.
We will discuss this more fully in Rule #4, Alignment below.
Rashi could find support for this abstention in verse Gn11-10
which states that Shem, Noah's eldest son, did not have his first
child till two years after the flood.
Text of Target Verse Gn06-08
Text of Reference Verse Gn11-10
But I will establish My covenant with thee; and thou shalt come into the ark,
- thy wife, and
- thy sons' wives with thee.
Go out from the ark,
- your sons, and
- your sonsĘ wives with you.
There was abstention from marital relations during the flood years.
Normal relations resumed after the flood years.
Advanced Rashi: We haven't actually proven that there
was abstention. The fact that Shem did not have his first child till after
the flood is consistent with abstention but does not prove it.
A more thorough discussion will take place below in Rule #4, Alignment.