Matthew was writing to followers of Christ sometime after the destruction of the Jewish temple in Jerusalem (Scholars suggest sometime between 80-100 CE). Without the temple as a visible symbol, and more than symbol, of Jewish identity, some leaders were concerned that the Jews would be secularized, assimilated into Roman identity.
In this passage, Jesus has two audiences: the crowds and his disciples. The crowds are potential converts; the disciples are those who have been following him. He is warning them against the Pharisees,who are the religious leaders, insiders.
We too often read this passage and others as conflicts between Christians and Jews. Jesus is not saying that Jews are wrong because they are Jews. He is saying that these particular Jews are wrong because they are not good Jews. Jesus is not rejecting the Torah, but is insisting that these insiders should not only preach the law, they should practice it, as well. (Look back at Psalm 119 for a view of the law as a joy and delight).
"Get over yourself," Jesus tells the leaders. Start carrying your share of the burdens."
Lectio Divina: Matthew 23:11-12