Psalm 129:6- "may they be like grass on the roof, which withers before it can grow."

Mud and clay was often used to build houses in the East, and as a result grass would sometimes sprout on their flat plastered roofs.

Roof grass is used as a symbol of speedy destruction, because the grass was weak and would soon wither away under the scorching rays of the sun (see also 2Ki.19:26 and Isaiah 37:27)