Thou, and Shear-Jashub thy son. The name Shear-Jashub, "a remnant shall return," may have been given to Isaiah's son by revelation, as Ewald thinks it was; or Isaiah may have given it to testify his faith both in the threats and in the promises of which he had been made the mouth-piece.
The command to take him with him on the present occasion was probably given on account of his name, that the attention of Ahaz might be called to it. The conduit of the upper pool is mentioned also in 2 Kings 18:17.
It was probably a subterranean duct which brought water into the city from the high ground outside the Damascus gate. Ahaz may have visited it in order to see that it was made available for his own use, but not for the enemy's.