In ancient times, a man lost his axe and suspected the neighbor's son had stolen it
From then on, he scrutinized his neighbor's son's every move: the way he walked seemed like an axe thief; his expression seemed like an axe thief; his speech seemed like an axe thief. In short, every single action of the neighbor's son seemed like that of an axe thief.
A few days later, the man who had lost his axe finally found it—he had carelessly left it in the mountains while chopping wood.
Once he found the axe, he watched the neighbor's son again and noticed that not a single one of his actions seemed like those of a thief anymore.
Later, the idiom "Suspecting the Neighbor of Stealing the Axe" came to describe baselessly suspecting others without factual evidence.
Source: *Liezi*, Chapter "Explaining Signs"
Meaning of the Idiom: Later, the Chinese idiom "疑邻盗斧" came to describe baselessly suspecting others without factual evidence.