Jesus rebuked the Pharisees during His earthly ministry, who had routinely watered down the holy and unassailable standards of the Old Covenant.
He specifically attacked their demands for honor and recognition among men, even though they were completely undeserving of any such title.
Not only could they not begin to call themselves teachers of the Law, but the True and Eternal Lawgiver stood in their midst:
"Do not seek to be called "Rabbi" -- that is, teacher.
Jesus is more than a teacher. He gave standards which restored the pristine holiness of God's law, so that no one would even think of trying to generate their own righteousness (Matthew 5-7)
Jesus then goes one step further: He is their master.
But Jesus as our Master is the exact opposite of what the world understands about Lordship:
"For even the Son of man came not to be ministered unto, but to minister, and to give his life a ransom for many." (Mark 10: 45)
He even explains as much in his excoriation of the Pharisees:
"Neither be ye called masters: for one is your Master, even Christ. 11But he that is greatest among you shall be your servant. 12And whosoever shall exalt himself shall be abased; and he that shall humble himself shall be exalted." (Matthew 23: 10-12)
Now, look further at the result of Jesus as our Master:
"And all ye are brethren."
Jesus put aside the man-made distinctions of hierarchy and preeminence among us. He also affirmed our family affiliation among one another.
Now, how else can we be brethren, if we do not have the same Father.
Because of Jesus, God is no longer our Creator, but our Father:
"For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father" (Romans 8: 15)
Jesus is our Master, a master who serves us, who reveals His -- and our - Father's heart.