The greatness of keeping Shabbos according to its laws is well-known as Chazal said that anyone who keeps Shabbos according to its laws even he serves idols like the generation of Enosh will have his sins forgiven. They said further that if only Klal Yisrael would keep two Shabbosos according to their laws they would be redeemed. They said even further that the keeping of Shabbos has the same value as all of the rest of the Torah. In the Midrash it says that Klal Yisrael would only be redeemed in the merit of Shabbos. The Chida writes that so that the redemption will be speedily and in our times we are compelled to keep the Shabbos and it is impossible to bring healing and recovery for our souls except by the keeping of Shabbos.
We give huge praise to Hashem that the vast majority of Klal Yisrael are holy and keep Shabbos and sanctify it with its pleasures. However, our pain is great about two things which have caused us much trouble as there are many people who are not careful not to speak profane speech on Shabbos. This is something which is strictly forbidden, and the general public do not know or understand that one who speaks unholy words on Shabbos is considered as having desecrated the Shabbos.
For behold, it is forbidden to say “I will do this thing tomorrow!” if it is referring to something which is forbidden to be done on Shabbos and even if he specifies that it is forbidden (as is the custom of many ignorant people) and says “I will do this thing without speaking about it on Shabbos” (Nischt Shabbos Geredt) or other similar expressions, it does not help or save him from the sin that he is committing, and it is actually a joke and farce, for how can he say that it is without speaking about it on Shabbos? He is lying as he has said it on Shabbos! It was only unwillingly that Chazal allowed people to greet each other on Shabbos!