"Every person must respect his mother and father, and keep My Sabbaths. I am God your Lord."
One who learns Torah on Shabbat, understands new things, says new insights, and perhaps even learns Kabbalah on that day, causes great respect for his mother and father.
Everyone is given an additional soul on Shabbat. It is this soul that makes his Shabbat learning special. When Shabbat ends, the additional soul returns to Heaven, and the righteous there ask it, “What did you learn? What new thoughts and insights have you suggested?” The soul retells everything it did, and its words bring this extra honor to the person's parents.
That is why the two subjects are connected in the Torah: one shows great respect to his mother and father by observing Shabbat, that is, by learning Torah on that day.
Art: John Frederick Peto - Still Life With Candlestick And Book