Every action has a reaction and we see that in everyday life.
The 1st reading gives an example from nature, that as the rain and snow come down from the heavens, it waters the earth, and makes plants grow and bear fruit.
The Lord uses that example to tell us that the Word that goes forth from His mouth must also enter into our ears and into our hearts so that we will know what He wants of us and to do His will accordingly.
So we must pay attention to God's Word and let it take root in our hearts and to bear fruit in our lives.
And we must also pay attention to the words that are coming out of our mouths.
Our words must also be the fruit of God's Word in that our words must be for the good of others, to encourage them and to help them walk in the ways of the Lord.
So too must be our prayer. Our prayer is not to be some babbling, as Jesus pointed out in the gospel, words that don't come from our hearts and which won't go up to God.
If our words are to be for the good of others, then our prayer should also lead us to do the good that God wants of us.
May the Word of God fill our hearts, and from what fills our hearts, may it be for the good of others and also for our good.