"My sheep hear My voice, and I know them, and they follow Me." John 10.27
What characterizes the relationship between shepherd and sheep is the shepherd's voice. No sheep from a certain flock follows the voice of a shepherd of another flock.
It was common that several shepherds would gather their respective flocks to drink from the same stream. But once their thirst was quenched, each sheep would follow the voice of their respective pastors.
The followers of the Good Shepherd, hear His voice and follow Him. That is, obey.
