Chasidut do Izajasza 58:14

Delightful Love, as stated, is only experienced as a gift bestowed from above. This level is identified with Shabbos, a day which is associated with the lofty spiritual level of “delight” or “pleasure” (ta’anug in Hebrew), as in the verses (Isaiah 58: 14 and 13), “[if you observe Shabbos…] then you will delight yourself in G-d,” and “you will call Shabbos a delight.” However, as the Talmud remarks (Avoda Zara 3a), “One who toils on the eve of Shabbos will eat on Shabbos,” that is, prior preparation is necessary to experience Shabbos properly. In our context, too, in order to experience the level of Delightful Love that is revealed on Shabbos, one must spend one’s week in sincere worship of G-d and toil in the effort to bring out both prerequisite levels, ahavas olam and ahava rabba.