This is a short statement but one full of meaning for the father who desires to teach his son true wisdom. This is because the godly father wants to teach his son the things of the Lord - the Scriptures. He knows that the fear of the Lord is the beginning of wisdom - and that this comes from knowing God according to His self-revelation to us, which we call the Bible.
The father here is pleading with his son not to forget the teaching (torah). This word speaks of the general instruction in the way of the Lord. This is something about which every father should be deeply concerned. He does not want his sons to forget or to lay aside in their minds the teaching about the Lord. This is the key to living a happy life - a life that God can use - and a life that will not bring His discipline upon it. The father pleads with his son for this simply because one of the sins that we see most often in the hearts of God's people is simply to forget this - the simple teaching of knowing, loving, and following the Lord.
The way this godly father addresses this need is by calling his son to let his "heart" keep God's commandments. Here is a key to having godly children. Speak to their hearts - not just their heads. Dad, be passionate about the things of the Lord so that when you speak, your sons and daughters will hear that passion and know you speak with them of things that are vitally important! This is not just religion that you practice for a hour or two on Sundays and Wednesdays - this is life itself. When we speak to our children's hearts - we are placing the Word in the most valuable place we can. We are stating to our kids that we want to win and maintain their hearts - not just for ourselves - but more importantly for the Lord their God.
Here is wisdom, Dad. Win and keep your child's heart. Speak for this purpose and you will have a child who will grow up not just "going to church," but living for God with all that they are and all that they have.