Commentary for Kiddushin 60:13

רבי יהודה אומר כל שאינו מלמדו אומנות מלמדו ליסטות ליסטות ס"ד אלא כאילו מלמדו ליסטות

Whence do we know it? - Said Hezekiah: Scripture saith, See to a livelihood with the wife whom thou lovest.<span class="x" onmousemove="('comment',' Ecc. IX, 9.');">³⁰</span> If 'wife' is literal, [this teaches,] just as he [the father] is bound to take a wife for him, so bound to teach him a craft [for a livelihood]; if it is [a metaphor for] Torah, then just as he is bound to teac him Torah, so is he bound to teach him a craft.' And some say, [He must teach him] to swim in water too.

Daf Shevui to Kiddushin