Found in Matthew 18:1-7,10,14, Mark 9:33-37 and Luke 9:46-48.
Jesus and his disciples were in the house in Capernaum.
Jesus: What was it that you disputed among yourselves on the way?
The disciples remained silent, for on the way they had disputed among themselves, who should be the greatest.
(Matthew says the disciples came to Jesus and said to him, “Who is the greatest in the kingdom of heaven?”)
Jesus (perceiving the thought of their heart – Luke 9:47): If any man desire to be first, the same shall be last of all, and servant of all.
And Jesus took a little child, and set him in the midst of them: and he took the child in his arms.
Jesus: Except ye be converted, and become as little children, you shall not enter into the kingdom of heaven. Whoever therefore shall humble himself as this little child, the same is greatest in the kingdom of heaven.
Whoever shall receive this child in my name receives me: and whoever shall receive me receives him that sent me: for he that is least among you all, the same shall be great.
But whoso shall offend one of these little ones which believe in me, it would be better for him that a millstone were hanged about his neck, and that he were drowned in the depth of the sea. Woe unto the world because of offenses! for offenses must come; but woe to that man by whom the offense comes!
Take heed that you despise not one of these little ones; for I say unto you, That in heaven their angels do always behold the face of my Father which is in heaven. It is not the will of your Father which is in heaven, that one of these little ones should perish.