Your testimonies I have taken as a heritage forever,
For they are the rejoicing of my heart
The word "heritage" is a bit old-fashioned, but I think most people still understand the concept: it simply means "an object or quality passed down from previous generations, an inheritance." It also contains the idea of being a special or individual possession—no two families will have exactly the same inheritance.
What better foundation for living life could a parent give their child than a knowledge of God's testimonies? In Philippians 3:8, Paul says that all other things he counts as loss in comparison with the excellence of the knowledge of Christ Jesus. Unlike material inheritances, it will never be used up, or crumble to dust, for Peter tells us that the word of God lives and abides forever (1 Peter 1:23). The world can never take it from us, because He who is in us is greater than he who is in the world (1 Jn. 4:4).
I am incredibly blessed to have the Word of God as my heritage. Growing up, I was saturated with the Bible—not just Sundays and Wednesdays, but in the home as well: reading and memorizing it together as a family, and each member individually. Not only was I surrounded by God's testimonies, I also saw that they were held in the highest esteem by everyone I respected. It was the standard by which behavior was judged: when we were corrected, it was not because our actions had been inconvenient to our parents, but because they had been contrary to God's commands. With this background, it was easy and natural for me to learn to love and revere Scripture.
Many people do not grow up in a home like mine, but they can still choose to take God's testimonies as a heritage. This is an inheritance that has to be personally accepted before it is legitimate; just following the letter of the law because everyone around you does is not enough—it must be a conscious choice to embrace this most excellent knowledge and let it shape your life. Having this heritage, we must guard it—do not let people take anything away from it—nurture it, by making sure our life matches up with our beliefs, and pass it on to those who come after us.
"If we might have our desire, we would desire to keep the commands of God perfectly. To know the doctrine, to enjoy the promise, to practice the command — be this a kingdom large enough for us."
- Charles Spurgeon