Yǎn jiàn wèi shí.
眼见为实。
Seeing is believing.
Notes:
眼(yǎn):eye
见(jiàn):to see
为(wéi): is
实(shí): truth
Example:
A:他说他有女朋友了。
Tā shuō tā yǒu nǚpénɡyǒu le.
He said he got a girlfriend.
B:眼见为实。
Yǎn jiàn wèi shí.
Seeing is believing.