Keith Simons explores Psalm 133, emphasizing the beauty of unity among God's people as they gather for sacred feasts in Jerusalem. He illustrates how the psalm reflects a vision of harmony, where brethren dwell together in peace, akin to the anointing oil on Aaron, symbolizing the Holy Spirit's work in bringing people together. Simons highlights the importance of sharing blessings and the promise of eternal life that God commands for those who worship Him in unity. The sermon encourages believers to foster relationships that reflect this divine unity and to recognize the blessings that come from being together in faith.