Carl Friedrich Keil and Franz Delitzsch Old Testament Commentary

The prophet might have ceased speaking now; but in accordance with the command in Isa 6:1-13 he was obliged to speak, even though his word should be a savour of death unto death. "And he spake, Hear ye now, O house of David! Is it too little to you to weary men, that ye weary my God also?" "He spake." Who spake? According to Isa 7:10 the speaker was Jehovah; yet what follows is given as the word of the prophet. Here again it is assumed that the word of the prophet was the word of God, and that the prophet was the organ of God even when he expressly distinguished between himself and God. The words were addressed to the "house of David," i.e., to Ahaz, including all the members of the royal family. Ahaz himself was not yet thirty years old. The prophet could very well have borne that the members of the house of David should thus frustrate all his own faithful, zealous human efforts. But they were not content with this (on the expression minus quam vos = quam ut vobis sufficiat, see Num 16; 9; Job 15:11): they also wearied out the long-suffering of his God, by letting Him exhaust all His means of correcting them without effect. They would not believe without seeing; and when signs were offered them to see, in order that they might believe, they would not even look. Jehovah would therefore give them, against their will, a sign of His own choosing.