Isru Chag
Question
What is Isru Chag? Are there any mitzvot I must perform?
Answer
Shalom!
Thank you for your question.
The day after Pesach, Shavuot, and Sukkot is indeed referred to as “Isru Chag” and has some degree of sanctity as it “connects” the holiday to our return to our mundane weekday activities and pursuits. The name “Isru Chag” derives from Tehillim 118:27 where it says “bind the festival offering (“Isru Chag”) to the corners of the altar.” Although it is a quasi-holiday there are no restrictions on work or the like.
Our sages teach that one who honors Isru Chag by eating and drinking is considered to have built an altar and offered a sacrifice. As such, one is encouraged to indulge in a more elaborate meal than usual on Isru Chag. Some have the custom to wear their Yom Tov clothes on Isru Chag, as well.
Isru Chag also recalls the pilgrims in ancient times who would return to their homes with renewed excitement and inspiration after having celebrated the holiday in Jerusalem.
SOURCES: Sukka 45b; Chagiga 17a; Rema, OC 429:2; Shulchan Aruch Harav 494:20; Torah Lishma 140