"And Moshe went up to God" (Exodus 19:3), because the great righteous person (tzadik) is called with the name "Moshe", and to this one there is an extra level above the other tzadikim, mentioned above, [the Moshe-type tzadik] goes up to the higher worlds: "and God called him" the words "and called" denote affection. "Thus shall you say to the house of Jacob" - those are the tzadikim that are not yet at that level, whose responsibility is to fix the Presence [of the Holy One] that is called [denoted] by the word "thus."
"And declare to the children of Israel" - these are the real tzadikim, who are known by the name Israel, whose responsibility is to the an extra work, that is difficult as tendons... Thus you will say to the house of Jacob and tell the Children of Israel - the energy in the word "thus" is a hint of all the blessings, as it is written "thus you will bless", "thus will be your seed." And the fact that most of the world needs sustenance and abundance, and to this our Creator of Blessed Name said to him [Moshe]: "thus you will say to the house of Jacob" - this is the monetary riches, called [denoted] by the name "Jacob", and the abundance which comes from the aspect "thus" continues for them, bringing blessing and physical abundance from there.
"And tell the Children of Israel" - those are the great ones, which are called by the name "Israel", and the higher light continues for them, putting a great love and awe from the higher worlds in their hearts. "And tell" - this is the language of continuation, giving them what they need from the higher worlds so they continue their work for their level of Gods work. And this is easy to understand.