Isaiah 8:16

Isaiah’s audience needed to return to God’s revelation and recommit themselves to it, which the prophet led the way in doing (cf. Joshua 24:14-15). Those who followed his lead became his disciples and disciples of the Lord.

"Once his [Isaiah’s] message had been rejected by the court (Isaiah 7:1-17) and the people (Isaiah 8:1-8), he turned to his disciples (Isaiah 8:16-18), thus preparing the way for the judgment that God had already pronounced (Isaiah 6:11-13)." Jesus did the same thing (cf. John 12-16).