1 Kings 1:33

Mules and horses seem to have been first employed by the Israelites in the reign of David, and the use of the former was at first confined to great personages 2 Samuel 13:29; 2 Samuel 18:9. The rabbis tell us that it was death to ride on the king’s mule without his permission; and thus it would be the more evident to all that the proceedings with respect to Solomon had David’s sanction.

Gihon - Probably the ancient name of the valley called afterward the Tyropoeum, which ran from the present Damascus Gate, by Siloam, into the Kedron vale, having the temple hill, or true Zion, on the left, and on the right the modern Zion or ancient city of the Jebusites. The upper “source” of the “waters of Gihon,” which Hezekiah stopped (see the margin reference), was probably in the neighborhood of the Damascus Gate.