(Mishnah - Beis Shamai): At night, one should [lie down and] lean [on his side] and recite [Shma]. In the morning, he should stand to say it -- "uv'Shachbecha uv'Kumecha";

Beis Hillel says, one should recite in whatever position he is -- "uv'Lechtecha va'Derech."

Question: If so, what do we learn from "uv'Shachbecha uv'Kumecha"?

Answer: We recite at the time that [most] people lie down and rise.

(Gemara) Question: [Our Mishnah teaches how] Beis Hillel fulfill two verses (theirs, and Beis Shamai's). How do Beis Shamai fulfill "b'Shivtecha b'Veisecha uv'Lechtecha va'Derech"?

Answer: "B'Shivtecha b'Veisecha" excludes one who is engaging in Mitzvos. "Uv'Lechtecha va'Derech" excludes a Chasan. (Even when not engaging in the Mitzvah, he is exempt due to distraction.)

(Beraisa): A case occurred in which R. Elazar ben Azaryah and R. Yishmael were staying in a place. R. Elazar ben Azaryah was reclining and R. Yishmael was erect. When the time for [the morning] Shma came, R. Elazar straightened himself and R. Yishmael reclined.

R. Elazar ben Azaryah (to R. Yishmael): [If one] said to a man in the market 'how nice is your long beard', and he says "it will be shaved off" [this is like you did]!

I was reclining, and I straightened up (to fulfill "uv'Kumecha"), and you, who were erect, reclined!

R. Yishmael: You straightened up like Beis Shamai. I reclined like Beis Hillel!

Also, perhaps Talmidim will see me [erect] and they will fix the Halachah permanently like Beis Shamai's words!