وَسُيِّرَتِ الْجِبَالُ فَكَانَتْ سَرَابًا (and the mountains will be set in motion, so they will be as mirage....78:20). The word suyyirat 'set in motion' signifies that mountains, which are taken as an example of firmness and strength, will be shifted from their positions, and will become like little particles of dust flying about in the atmosphere. The word sarab literally means 'to disappear' and it also refers to 'mirage' or an optical illusion, as of a sheet of water, that sometimes appears in a desert, because it seems to be a sheet of water from a distance, but when a person comes near it, it disappears. [ Sihah and Raghib ].