Aliya Summary: The Israelites were left traumatized by the overwhelming revelation, the awesome “light and sound” show. They turned to Moshe and asked that from thereon he serve as an intermediary between them and G‑d—Moshe should hear G‑d’s word and transmit it to the people. Moshe agreed. The reading concludes with a prohibition against creating idolatrous graven images – considering that no image was seen when G‑d revealed Himself on Mount Sinai – and the commandment to erect a sacrificial altar. The altar stones should not be hewn with iron implements, nor should there be steps leading to the top of the altar.
Metal implements represent the sword, which shortens life; the Altar represents the lengthening of life. From this rule comes the custom to remove or cover the bread-knife during Birkat HaMazon, since our table is likened to the Altar.