The Beraisa taught that a father must teach his son a trade.

Beraisa (R. Yishmael): The pasuk states (Devarim 30, 19), "and you shall choose life'' - this refers to having a trade.

He must marry him to a woman - the pasuk states (Devarim 4, 9), "and you shall inform your children and your children's children - when do you merit to have children and children's children? When you marry your sons to women when they are young.

R. Akiva said that he must also teach his son to swim, as the pasuk states (Devarim 30, 19), "...in order that you and your offspring shall live''.

Question: Are all of these mere Mitzvos or are they obligations (that Beis Din can force the father to fulfill)?

Proof: Bar Terimah came before R. Ami and said to him, "Convince my father to marry me a woman''. R. Ami appeased the father but he refused. This shows that it is merely a Mitzvah, as had it been an obligation, R. Ami would have forced him.

Question: From where is it known that if the father did not perform these Mitzvos, that son must perform them himself?

Answer: The pasuk states (Shemos 13, 13), "You shall redeem every human (firstborn amongst your sons)''. The word "human'' is extra to teach that it should be read that either a person should redeem himself, or a father should redeem his child.

Similarly for the following three Mitzvos - (Bereishis 17, 11), "And you shall circumcise'' - also yourselves; (Devarim 11, 19), "You shall teach them'' - also to yourselves; (Devarim 4,9), "and you shall inform'' - also yourselves.