It may be the LORD thy God will hear the words of Rabshakeh, whom the king of Assyria his master hath sent to reproach the living God, and will reprove the words which the LORD thy God hath heard: wherefore lift up thy prayer for the remnant that is left.
Hear - take cognizance of them (2 Samuel 16:12).
Reprove - will punish him for the words, etc. (Psalms 50:21).
Remnant that is left - the two tribes of the kingdom of Judah, Israel being already captive. Isaiah is entreated to act as intercessor with God.