What are the ramifications of the words "La'asos es ha'Shabbos"?
Seforno: The Pasuk is saying that if Yisrael will keep Shabbos in this world, they will merit to keep Shabbos in the world to come.
Targum Yonasan: It means to eat delicacies on Shabbos.
Mechilta: It teaches us that when someone keeps Shabbos it is considered as if he made Shabbos. 1
Mechilta: In conjunction with "La'asos es ha'Shabos" it teaches us that one is permitted to perform the B'ris Milah 2 if it falls due on Shabbos.
Why does the Torah here insert "Veshamru" before "Shabbos" and in Kedoshim Vayikra, the reverse, when it writes in 19:3 "Es Shabsosai Tishmoru"?
Moshav Zekenim (in 16:23): The current Pasuk teaches us that Shabbos requires Shemirah before - 'A tailor may not go outside carrying a needle close to Shabbos', and the Pasuk in Kedoshim, that it requires Shemirah afterwards - 'One may not benefit from Melachah that was done on Shabbos'.
Mechilta: The current Pasuk teaches that one must add from Chol on to Kodesh before Shabbos comes in, the Pasuk in Kedoshim, that one add on to Kodesh after it goes out (Tosefes Shabbos). 1
The Mechilta d'R. Yishmael (in Yisro, Masechta d'Chodesh 7 DH 'Zachor') learns Tosefes Shabbos before and after from 'Zachor' and 'Shamor', respectively.
