Elongation along the tongue edge

The mechanic

The sound of ض travels along the edge of the tongue from the rear molars forward toward the front, so it takes up a stretch rather than a point.

Where it occurs

The istitala letter

ض

A place in the text

وَٱلضُّحَىٰ

The marked spot was located in this ayah's own text at build time — Ad-Duha 93:1.