English: It was taught: Slaves are exempt from Keri’as Shema, as it is said “Hear, O Israel, Hashem is our God, Hashem is One” — one who has only one Master; this excludes a slave who has another master.
On the daf / in context: The declaration of exclusive divine sovereignty is incompatible with the legal status of one who already has a human master.
Type of Learning
Diyuk of “Hashem Echad” as requiring exclusive subjection to one Master.
What Is Learned
A slave is exempt from Shema because the verse addresses one who has no master other than Hashem.