Shabbos is The Test

The Rebbe of Barnov zy”a (Sefer Chamra Tova) explains that there are men who have to work hard all week in order to make a living and, as a result, cannot learn very much Torah. How can we know if they really want to learn but simply cannot do so? The way to determine this is to see if they learn on Shabbos, when they do not have to work. If such a person uses Shabbos for learning Torah and serving Hashem, it proves that his intentions are good and it is considered as if he learned all week.

Accordingly, the pasuk is saying: “Rak shivto yitein” – if one gives his all on Shabbos and honors this day by learning Torah and serving Hashem, he will then be “healed” and considered someone who serves Hashem at all times.