(Devarim, Ibid.) "to explain this Torah, saying": He said to them: I am about to die. Anyone who heard one verse and forgot it, let him come and review it. Anyone who heard one section and forgot it let him come and review it and understand it. This is the intent of "to explain this Torah."
(Devarim 1:6) "The L-rd our G-d spoke to us in Chorev to say": He said to them: It is not of myself that I am telling you, but from the mouth of the Holy One Blessed be He.