Setting and Overview
As Jesus moves through the Sermon on the Mount, we see Him skillfully address common erroneous beliefs that existed among the people, head off objections to His teaching that could have arisen, demonstrate the application and relevance of His commands, and even correct misunderstandings or misapplications before they are even voiced. We see an example of the last one here in Matthew 6:1, in a verse that serves as an opening to the seventeen verses that follow. As people grow in their obedience to Jesus’ commands throughout chapter 5, a dangerous pride is likely to develop, and people are likely to become very eager to prove to others just how much more righteous they are. In verse 1, Jesus gives a sharp warning against such behavior, and then will spend the first half of chapter 6 addressing three specific areas in which this is likely to arise.

Exposition
The warning to “be careful” is a sharp one (Matthew 7:15, 10:17, 16:6) and would have certainly gotten people’s attention. “Righteousness” can refer to our standing, our obedience, or our orientation toward God, and while not all aspects of righteousness will be external or visible, true righteousness will be reflected in external actions (Psalm 106:3, Isaiah 58:1-7, I John 2:29, 3:7-10.) In the following verses, Jesus will refer multiple times to “hypocrites,” which was often used to refer to actors, but in this case is meant more broadly to those who are being insincere or pretending to be something that they are really not, a charge that He levels against Pharisees (Matt 23:5.)
In some ways, this verse could seem to come into conflict with Matthew 5:16, but in comparing the context and specific exhortations of each, we see that they actually complement each other. The wording in 6:1 refers more specifically to putting on a show or performance for someone, whereas 5:16 refers to simply being observed. Also 6:1 warns against doing things for the explicit purpose of being seen so that others will honor us, whereas 5:16 refers to honor being given to God, not to us. So Jesus is affirming that we should do righteous deeds, but warning us that what we do and how we do it should be dictated by what will please and give honor to God, not what will bring us acclaim.
Jesus’ exhortation also comes with a warning of our loss of heavenly rewards. He will speak in more detail about such rewards later in the Sermon on the Mount (Matthew 6:19-21.) It is important for us to remember even here, however, that we our actions and obedience will be judged and evaluated, and we are commanded to be motivated by a desire for those actions to please God (II Corinthians 5:9-10.)

Examination and Application
It is easy for us to feel good about ourselves because we don’t think that we go out of our way to promote our good works, but when we dive deeper, it is easy to find areas for need for growth. Do we look for opportunities to let people know how hard things are for us? Do we get upset when others get credit for things that we have done? Are we more likely to accept public service opportunities for which we will receive credit than for private ones that few people will ever know about? Are we more likely to declare publicly our devotion to Jesus than to privately spend time in prayer and Bible study? Do we ever perform ministry opportunities while thinking about whether or not others will appreciate and praise us for what we are doing? Unfortunately, if we look closely enough, all of us can find evidence that we are too motivated by the approval of others and not motivated enough by the approval of God. As we move forward in this chapter, Jesus will challenge us on specific areas in which this is likely to be true.