The last letter of the word Shema and Echad is larger than the rest of the letters and forms the word עד, witness. Rabbeinu Bachya states that Hashem Himself is witness to the level of concentration and listening we do when we say Shema and to His Unity and our acceptance of His Ol Malchus Shamayim upon ourselves.
He explains how we must hear with our ears and open our heart to what we are about to hear.
And he says it is required upon us to do this to fulfill our requirement of the recital of Shema, and relating to Hashem’s Unity. Gan Eden is the response for those who acknowledge Hashem’s Unity with heart and ears. (Devarim, 6:4)
One has to open one’s ears and heart to listen.. In regards to Hashem’s Unity.
Doing so is necessary as part of our mitzvah to be Mikabel Ol Malchus Shamayim.
It is only one who listens properly to the matter of Hashem’s Unity that Gad Eden is prepared for.
Hashem Himself bears witness to the authenticity of our Shema.
Why does Hashem Himself bear Witness to our level of concentration?
Does He not do that for all things? What is unique about this type of Bearing Witness?
How does listening with our ears and heart lead to love of Hashem, the next directive?
Is it possible that this type of listening of His being an Echad , is what unlocks our hearts to love Hashem?