Jamieson, Fausset and Brown on Jeremiah 19:2

2. valley of the son of Hinnom--or Tophet, south of Jerusalem, where human victims were offered, and children made to pass through the fire, in honor of Molech.

east gate--Margin, "sun gate," sunrise being in the east. Maurer translates, the "potter's gate." Through it lay the road to the valley of Hinnom (Jos 15:8). The potters there formed vessels for the use of the temple, which was close by (compare Jr 19:10, 14; Jr 18:2; Zec 11:13). The same as "the water gate toward the east" (Ne 3:26; 12:37); so called from the brook Kedron. Calvin translates, as English Version and Margin. "It was monstrous perversity to tread the law under foot in so conspicuous a place, over which the sun daily rising reminded them of the light of God's law."