Leah has six sons – her full complement. It is analogous to working 6 full days, as we are commanded to do.
What blessing does she ask for?
And Leah said, God has endowed me with a good dowry; now will my husband dwell with me, because I have born him six sons: and she called his name Zevulun.
The word “dwell” is not quite right – the word in the Torah is zaval which only appears here in the Torah, so the meaning is not obvious. It might alternatively mean “exalt” or “prize.” Nevertheless the word is linked to ishi, “my husband.”
Leah is saying that now that she has produced six sons, she merits a special connection to her husband.
Might this be a beautiful mirroring of another famous example?
After all, we are positively commanded to work for 6 days each week. And then, if we do, there is a great reward and connection that results from it!
Just as Leah made six sons and she earned a special connection to her husband, so, too, if we work six days, then we merit a special spiritual connection with G-d in the form of Shabbos!