"What I tell you in the dark, speak in the daylight; what is whispered in your ear, proclaim from the roofs." (Matthew 10:27)

Jesus is telling his students to pass on his teachings to others. This is a critical part of his mission. He carried on the teachings of his teacher, John the Baptist, and expected his students to do the same.

This is the process of how knowledge is passed from teacher to student, as was followed over thousands of years through the prophets from Abraham to John the Baptist. This is the process the Supreme Being uses to pass His message through: Through devoted messengers who have learned to love and serve Him.

While Jesus may have instructed them in private, he expected them to follow those teachings and then broadcast them to others.

And while the Supreme Being instructed them on what to say from within, Jesus wanted to them teach those instructions to everyone. This was also expressed by Jesus earlier:
"But when they arrest you, do not worry about what to say or how to say it. At that time you will be given what to say, for it will not be you speaking, but the Spirit of your Father speaking through you." (Matt. 10:19-20)
This same statement was recorded slightly differently in Luke:
"When you are brought before synagogues, rulers and authorities, do not worry about how you will defend yourselves or what you will say, for the Holy Spirit will teach you at that time what you should say." (Luke 12:11)
This might bear the question: Why did Jesus' students need Jesus as their teacher if the message comes from the Supreme Being from within?

The spiritual teacher provides the introduction to the Supreme Being, and guides the student in practical ways according to the time and circumstance. He also provides an example to follow. This is a living process. It is a process of relationships. Just as a friend will introduce us to their friend, the Supreme Being utilizes those who love Him to re-introduce us to Him.

You see, the Supreme Being is not a vague force or burning bush. He is a person - albeit the Supreme Person. The Supreme Being enjoys loving relationships.

And this is why we are attracted by loving relationships. Because we were created by the Supreme Being. We come from Him. And this is why Jesus, Moses and other representatives of God taught the same message:
"Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.’" (Mark 12:30)

 (For a translation of Jesus' statements from the Book of Matthew without institutional sectarian influence, see the Gospels of Jesus  - translated from the original Greek texts.)