There is a widespread custom to go to a body of water on the first day of Rosh Ha-shana and recite several verses, including “He will cover up our iniquities; You will hurl (tashlikh) all our sins into the depths of the sea” (Micha 7:19). For this reason, the practice is referred to as Tashlikh. Over time, many communities added various other prayers and verses.
The custom of reciting Tashlikh began in the Rhineland – the heartland of Ashkenaz – during the medieval era. Over time, the custom spread to Sephardic communities as well, especially after Arizal praised it. However, there is no obligation to recite Tashlikh, and some Torah giants did not observe this custom (Vilna Gaon; R. Ḥayim of Volozhin). Most Yemenites do not say it either. Some Ḥasidim recite Tashlikh on a weekday following Rosh Ha-shana.
Various explanation for this custom are offered. Some say that it is meant to remind us of the dedication of our forefathers Avraham and Yitzḥak; when they were on their way to the Akeida, their path was suddenly blocked by floodwater, which they forded, passing the test (Maharil). Additionally, water symbolizes purity and life. When a person elevates himself through repentance, he is purified and cleansed. It is as if his sins are washed away in purifying waters. Furthermore, Tashlikh includes a petition to God to cast all the accusers created by our sins into the depth of the seas and never be recalled. Some people shake out their clothing when they recite Tashlikh, demonstrating that whatever sins they have committed are external to them, the result of evil influences that we are now shaking off.
Historically, most women did not recite Tashlikh. Some even say that it is preferable for them not to do so, in order to avoid the mingling of the sexes (Elef Ha-magen 598:7). Nevertheless, women who wish to participate may do so.
When there is no natural body of water nearby, it is customary to recite Tashlikh by a well or cistern. Where a sea or stream is visible, even at a distance, some recite it.