Word: 真人 (zhēnrén)

当着真人，不说假话

dāngzhe zhēnrén, bù shuō jiǎhuà

before a person who knows the truth, tell no lies

狗咬吕洞宾，不认识真人

gǒuyǎolǚdòngbīn, bú rènshi zhēnrén

a dog bites Lü Dongbin: it doesn't recognise a true immortal

真人不露相，露相不真人

zhēnrénbúlòuxiàng, lòuxiàng bù zhēnrén

a true master doesn't show his face; one who shows his face is no true master

真人面前说不得假话

zhēnrén miànqián shuōbùde jiǎhuà

you can't tell lies before a real master