At first glance, verse 3 appears to say that dreams are an echo of our daytime activities, that anxious days cause troubled sleep. While that is certainly true, the verse appears in the context of how to worship God. Thus Solomon advises, "Prioritize and keep your life simple!"
"Walk prudently" means "watch your moral conduct." Frequently, "hear" is used synonymously with "obey," and the "sacrifice of fools" is allowing fellowship to degenerate into mere socializing without serious regard toward walking prudently and hearing God.
Hastiness in prayer is speaking ill-considered words before God. Though we pour out a prayer to Him in anguish, we may not think about the possible effects of our words. We can also do this by praying carelessly, ignorant of the seriousness of our communication with God.
What causes hastiness in prayer? A multitude of business. The busy fool pours out a flood of useless words because his mind is crammed with all the details of his business. This evil excess misuses important time with God and obscures the effectiveness of simple, heartfelt, and thoughtful prayer. When our minds are so full of our own activities rather than with the purposes of God, we often pray to Him like fools who talk incessantly about things of no consequence, or we endlessly repeat ourselves.