Jesus told us that if we love Him we will keep His word. (cf. Jn 14:23). In the first reading Moses tells the people that they should not add or subtract from what God told him to tell them. Human nature is such that we would prefer to craft God’s word to us to suit our desires. That is not submitting to the word that had been planted in us. And if we do not submit, we will be unable to bear the fruit that we have been created to bear.
The Mass readings can be found here: Scripture Readings
The blog post can be found here: Blog Post