妄断

wàng duàn shì fēi

妄断是非

make a rash judgement about what is right and what is wrong

cǐ shì bù néng píng kōng wàng duàn

此事不能凭空妄断。

On no account should any unfounded conclusion be made on this matter.

zhēn xiàng dà bái zhī qián nǐ bù néng zuò rèn hé wàng duàn

真相大白之前你不能做任何妄断。

You can't jump to a conclusion before the case becomes entirely clear.