הלכה על סוכה 83:10

From the laws of the commandment: That which they, may their memory be blessed, said (Sukkah 42a) [that] from when does a father begin to teach his son Torah? From when he begins to speak, he should teach him, "Moshe commanded us the Torah" (Deuteronomy 33:4), and the first verse from the recitation of Shema, which is "Hear Israel" (Deuteronomy 6:4). And afterwards he teaches him a little [at a time] of the verses of the Torah, until he is six or seven, when he takes him to a teacher of infants. And it is fitting for every intelligent person to put his heart to not overburden the child with study when he is still weak-limbed and weak-hearted, until he he grows and his strength firms, his limbs become vigorous, his bones fill with marrow and he can endure the exertion of study, and that the illness of fainting [spells] not happen to him on account of much exertion upon it. However after his strength firms and his eyes enlighten to understand the voice of his teachers, then is the thing proper and fit; and he is [then] obligated to put his neck to the yoke of Torah [study], and not to loosen it from him, even a hair's breadth. And he should [then] always give him to drink from its spiced wine, and feed him from its honey.