Mattityahu 18:1-5

At that time, the talmidim approached Rebbe, Melech HaMoshiach with this she'elah saying, Who then is greatest in the Malchut HaShomayim? And having called a yeled to himself, he set him before them, and said, Omein, I say to you, unless you change inwardly and have a complete turn around and become like yeladim, you shall never enter the Malchut HaShomayim. Therefore, whoever humbles himself as this yeled, he is the greatest in the Malchut HaShomayim. And whoever receives one such yeled in my Name receives me.