柠檬不该羡慕西瓜西瓜不该羡慕柠檬
[níng méng bù gāi xiàn mù xī guā xī guā bù gāi xiàn mù níng méng]
The phrase means 'Neither lemons should envy watermelons, nor watermelons lemons.' This expresses that each has its own uniqueness and strengths; it's futile to compare or envy others since everyone has their distinct characteristics.