Ahaz went to Damascus, to meet Tiglath-pileser. — The great king appears to have held his court there after the capture of the city, and to have summoned the vassal princes of Palestine thither to do him homage in person before his departure. (See the Note on 2 Kings 16:8.)
And saw an altar. — Rather, and he saw the altar, namely, that of the principal Temple. Upon the account which follows Prof. Robertson Smith well remarks that the frivolous character of Ahaz “was so-little capable of appreciating the dangers involved in his new obligations, that he returned to Jerusalem with his head full of the artistic and religious curiosities he had seen on his journey. In a national crisis of the first magnitude he found no more pressing concern than the erection of a new altar in the Temple on a pattern brought from Damascus. The sundial of Ahaz (2 Kings 20:11), and an erection on the roof of the Temple, with altars apparently designed for the worship of the host of heaven (2 Kings 23:12), were works equally characteristic of the trifling and superstitious virtuoso, who imagined that the introduction of a few foreign novelties gave lustre to a reign which had fooled away the independence of Judah, and sought a momentary deliverance by accepting a service the burden of which was fast becoming intolerable” (Proph. of Israel, p. 251).
Urijah the priest — i.e., the high priest, who appears to be identical with the “credible witness” of Isaiah 8:2. His high official position would secure Urijah’s credit as a witness.
Fashion... pattern... workmanship. — These terms indicate that the king’s interest in the matter was artistic rather than religious.