The crowds who followed Jesus when he came down from the mountain came from hearing his sermon there. Being in awe of his authority in his speaking (Matthew 7:28–29), they will now be amazed (Matthew 9:33) by his deeds (Matthew 8:1–9:38)—just as he had earlier both proclaimed and demonstrated the power of the kingdom of God (Matthew 4:23–25).
Those same people who had initially stood in awe of the teachings of Jesus during the Sermon on the Mount (Matthew 7:28), now followed him. In doing so, they are also given the opportunity to see even more wonders and be even more amazed (Matthew 8:27, Matthew 9:33). In Matthew 8:1–34 and Matthew 9:1–38 the evangelist describes no less than ten wonders. The Sermon on the Mount recorded in Matthew 5-—7 constituted the teachings of the kingdom of heaven, while the next two chapters reveal the power of that kingdom (see also Matthew 4:23).1 The crowds therefore proceeded to follow Jesus immediately following the Sermon on the Mount.2
1 When he came down from the mountain, great crowds followed him.