Keith Simons teaches on Psalm 127, emphasizing that without God's involvement, all human efforts to build and protect our lives are in vain. He explains that the psalm, attributed to Solomon, highlights the importance of relying on God for success in our endeavors, whether building a home or safeguarding a city. Simons illustrates that children are a divine blessing and heritage, essential for the continuation of God's work through generations. He encourages believers to trust in God's provision and guidance, as true success comes from Him, not merely from our hard work. The sermon concludes with the assurance that those who trust in God will not be ashamed when facing challenges.