Devarim 

דברים

Moses blessed the Israelites that they should multiply one thousand times over, but this blessing did not come to limit the blessings that the patriarchs had already received. Moses’ blessing was his own personal addition, while the blessings given to the patriarchs remain in effect. 

“The Lord, God of your fathers, will add to you one thousand times as you are, and He will bless you, as He spoke to you” (Deuteronomy 1:11). The Israelites said to Moses: Moses our teacher: We do not want you to bless us. The Omnipresent promised Abraham our patriarch: “For I will bless you and multiply your descendants as the stars of the heavens, and as the sand that is upon the seashore” (Genesis 22:17), and you impose limits upon our blessings. 

This can be explained by means of a parable of a king who had much property and a young son. The king had to travel overseas. He said: If I leave my property in the possession of my son, he will go and squander it. Rather, I will appoint a steward until he grows up. When that son grew up he said to the steward: Give me the silver and gold that my father left me in your possession. The steward went and gave him enough silver and gold to support him from his, the steward’s, own possessions. That son began getting upset. He said to the steward: But you have all the silver and gold that my father left me in your possession; why did you give me so little? The steward told him: Everything that I gave you was from my property, and what your father left you is still guarded. 

So, too, Moses said to Israel: “The Lord, God of your fathers, will add to you one thousand times as you are”; that is your blessing from me. And your blessing from God is: “And He will bless you, as He spoke to you.” Like the sand of the seas, like the plants of the earth, like the fish of the sea, and like the stars of the heavens in abundance. <source>(Sifrei Devarim, Devarim 11) </source>