Today's Gospel is a continuation of Jesus' instructions to the Twelve. It's not totally encouraging: "I'm sending you like lambs among wolves... They will haul you before judges..." And then he tells them not to try to come up with good arguments in their own defense. Leave that to the Holy Spirit when the time comes.
It's consistent with the Sermon on the Mount: do not trouble yourself about tomorrow. Live in the present moment, with profound confidence in God.