In Arabic, the word سراب (sarab) means mirage, whereas the word شراب (sharab), which looks almost identical, means drink. The similarity in how these words look is no coincidence; it’s actually part of the meaning. When you see a mirage, it looks just like water, a drink.
Allah uses this word, سراب, and its metaphorical value to describe the state of the mountains on the Day of Judgement.
وَسُيِّرَتِ الْجِبَالُ فَكَانَتْ سَرَابًا
And the mountains are made to vanish as if they had been a mirage
We percieve mountains as massive, unshakable structures, but Allah causes them to weightlessly float through the sky. In the same way, we often consider ourselves as established and secure, but what sense does that make, when objects so much more powerful than us will become like mirages?