海不曾怀疑天的蓝天不曾质疑海的碧
[hăi bù céng huái yí tiān de lán tiān bù céng zhì yí hăi de bì]
The literal meaning is 'the sea never doubts the sky's blue, and the sky never questions the sea's turquoise.' It represents mutual trust and harmony between two parties, often used to describe an ideal romantic or deep friendship relationship without suspicion.