a rope of sand
rope of sand
Something that is not as strong or stable as it seems. Yes, you're a fool to trust him, and this allegiance will soon prove to be a rope of sand. I thought I finally had a strong bond with my mother, but it was just a rope of sand—she's left us once again.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a rope of sandused in allusion to something that provides only illusory security or coherence. literary
Farlex Partner Idioms Dictionary © Farlex 2017