Relying on his promise was like depending on a broken reed.
Полагаться на его обещание было все равно что полагаться на ненадежную опору.
Definitions
A 'broken reed' is a metaphorical phrase used to describe something or someone that is unreliable or weak, especially when relied upon for support or help. The phrase originates from the idea that leaning on a broken reed (a type of plant stem) would not provide support and would likely break further, causing harm or disappointment.