Who will go for Us?: The Lord spoke in the presence of his angels. The Bible sometimes describes this gathering as a heavenly council (a group of heavenly beings who stand before God; see also 1 Kings 22:19–22; Jeremiah 23:18, 22).
Here am I: Isaiah answered quickly and willingly. God had just forgiven and cleansed him from sin. Because of this grace (God’s undeserved kindness), Isaiah was ready to serve.
He committed himself to a lifetime of ministry (service for God).