All the Jewish people, men, women, and children, would come to the assembly of all the Jewish people [hak’hel] staged during the eighth year of the Sabbatical cycle at the conclusion of the festival of Sukkot. According to the Sages, even though the children would not understand the Torah that was taught there, their parents fulfill a mitzva and receive reward by simply bringing them.

“Assemble the people, the men and the women and the children” (Deuteronomy 31:12). If men come to learn and women come to hear, why do the children come? They come in order for God to give reward to those who bring them. (Ĥagiga 55a)