What's the most important?

You must love the Lord your God with all your heart, all your soul, and all your mind. This is the first and greatest commandment. A second is equally important: Love your neighbour as yourself. The entire law and all the demands of the prophets are based on these two commandments.

A Solid Foundation

Anyone who listens to my teaching and follows it is wise, like a person who builds a house on solid rock. Though the rain comes in torrents and the floodwaters rise and the winds beat against that house, it won't collapse because it is built on bedrock. But anyone who hears my teaching and doesn't obey it is foolish, like a person who builds a house on sand. When the rains and floods come and the winds beat against that house, it will collapse with a mighty crash.

Materialism

Don't store up treasures here on earth, where moths eat them and rust destroys them, and where thieves break in and steal. Store your treasures in heaven, where moths and rust cannot destroy, and thieves do not break in and steal. Wherever your treasure is, there the desires of your heart will also be.

Forgiveness

... the Kingdom of Heaven can be compared to a king who decided to bring his accounts up to date with servants who had borrowed money from him. In the process, one of his debtors was brought in who owed him millions of dollars. He couldn't pay, so his master ordered that he be sold—along with his wife, his children, and everything he owned—to pay the debt.
But the man fell down before his master and begged him, 'Please, be patient with me, and I will pay it all.' Then his master was filled with pity for him, and he released him and forgave his debt.
But when the man left the king, he went to a fellow servant who owed him a few thousand dollars. He grabbed him by the throat and demanded instant payment.
His fellow servant fell down before him and begged for a little more time. 'Be patient with me, and I will pay it,' he pleaded. But his creditor wouldn't wait. He had the man arrested and put in prison until the debt could be paid in full.
When some of the other servants saw this, they were very upset. They went to the king and told him everything that had happened. Then the king called in the man he had forgiven and said, 'You evil servant! I forgave you that tremendous debt because you pleaded with me. Shouldn't you have mercy on your fellow servant, just as I had mercy on you?'

Obviously, the king in Jesus's story was far from impressed. We're only human, and fall far short of God's excellence. If we can accept God's forgiveness (and i recommend we do) then surely we can pass on just a little bit on to those we might think have fallen short of the mark.