Shuckling (also written as shokeling), from the Yiddish word meaning "to shake", is the ritual swaying of worshipers during Jewish prayer, usually forward and back but also from side to side. This practice can be traced back to at least the eighth century, and possibly as far back as Talmudic times. It was said of Rabbi Akiva that when he prayed by himself he would start in one corner and end up in another, because of all his kneeling and bowing. It is believed to increase concentration and emotional intensity (Eisenberg 2004:360). In Chassidic lore, shuckeling is seen as an expression of the soul's desire to abandon the body and reunite itself with its source, similar to a flame's shaking back and forth as if to free itself from the wick (Tanya chapter 19). Jiri Langer gives a vivid description of shokeling among Belz Chassidim in early 20th Century Europe.
The 12th century Jewish philosopher and poet Yehuda Halevi wrote that the habit began as a result of a shortage of books, forcing people to hover over a single codex laid on the ground, each one bending in turn to read a passage (The Kuzari, part II, para. 80). By the 13th century, Jews in Europe were “known for their shokeling during prayer.” 19th Century Jewish religious reformers, however, argued for the non-Jewish custom in which “no one moves a limb”.
Dr. Simon Brainin says that the practice was historically done "to afford the body exercise during study and prayer, which took up a large portion of the time of a great number of Jews".