At that time the disciples came to Jesus and asked, "Who is the greatest in the kingdom of heaven?"
References for Matthew 18:1
Then he called a little child over to sit among the disciples,
and said, “I assure you that if you don't turn your lives around and become like this little child, you will definitely not enter the kingdom of heaven.
Those who humble themselves like this little child will be the greatest in the kingdom of heaven.
Whoever welcomes one such child in my name welcomes me.