The Tiferes Shlomo says that this pasuk is talking about people who are more concerned with the frivolities of this world than with properly fulfilling the mitzvos of Hashem. Although they go to davening, their hearts are not in it. However, when it comes to their children, they are very strict with them and force them to go to school and not to waste a minute of learning or davening. While they have no low standards for themselves, they have high standards for their sons.
Accordingly, the pasuk is saying that one should be careful not to fail to protect to himself and to allow the ways of Hashem to depart from his own heart while simultaneously “making them known to his children” by chastising them and forcing them to do the right thing. Rather, one must first teach himself how to fear Hashem, and only then can he teach his children.
My ancestor, Rav Eliezer Zev of Kretchnif zy”a once took note of a man who didn’t act properly himself but was discipling his child by hitting him in the bais medrash. He told the man, “Why are you striking your son? You should be hitting yourself. He is simply following your example!”
It is related that a man once approached the Kotzker Rebbe zy”a and asked for a bracha for his sons to learn Torah. The Rebbe replied, “You should learn Torah, and your sons will follow your example. If you don’t learn, your sons also won’t learn... and they will come for brachos for their sons, but no one will ever learn on their own.”
