Matthew 5:3-11 is where what has become known at the Beatitudes is found. This is also the beginning of the Sermon on the Mount. In Luke 6, there is a similar passage, 6:20-26 being blessings and woes beginning the Sermon on the Plain.
A leader in one of the Christian groups I was involved in in college suggested that a way to grow in your faith is to memorize the Beatitudes, and then, once you had done that then memorize the rest of the Sermon on the Mount. Good idea. You can also do the same thing with Luke’s Sermon on the Plain. It’s shorter.