The man from [the ancient kingdom of] Qǐ fears the sky is falling
To have groundless or baseless fears
Negative
我表弟什么都怕，甚至杞人忧天到连自己的影子都怕 | Wǒ biǎo dì shénme dōu pà, shènzhì qǐrényōutiān dào lián zìjǐ de yǐngzi dōu pà
My cousin is afraid of everything. He's such a worrier that he's afraid of his own shadow
[Source]
别那么杞人忧天嘛, 一点小小的摇晃不会把房子震垮的 | Bié nàme qǐrényōutiān ma, yīdiǎn xiǎo xiǎo de yáohuàng bù huì bǎ fángzi zhèn kuǎ de
Don't a worrywart. A little shaking won't knock down this house
[Source]
Be afraid the sky is falling
Be a worrywart
杞人之忧 (qǐ rén zhī yōu)
None
《列子》(Liè Zǐ), a set of Daoist texts said to be by the author of the same name. He is said to have lived during the Warring States period (475 - 221 BC)
There was once a 杞国 (Qǐ Guó, a vassal state of the Zhōu Dynasty (周, 1046 - 256 BC)) man who was petrified that either sky would fall and crush his head or the ground would collapse and bury him alive. In fact, he was so petrified that he was unable to eat and sleep well. A friend noticed this behavior, and one day he drew him aside and explained, "The sky is just gas, and there's gas everywhere, even here as we breathe and move. Why are you worried that it's going to fall?"
The worried man replied, "Okay, but if the sky is just gas, then won't the sun, moon, and stars fall as well?"
His friend told him, "They're just bodies that emit light within the gas. Even if they did fall, they wouldn't hurt you."
This still didn't entirely soothe the man. He persisted, "But if the ground collapses, what will we do?"
His friend told him, "The ground is just accumulated bits of earth, and there is earth everywhere. Everything you do all day is on the ground. Why would you worry that it would collapse?"
These last words, finally, soothed the worried man's fears.