俗話說

as the proverb says / as they say...

custom / convention / popular / common / coarse / vulgar / secular

common saying / proverb

dialect / language / spoken words / speech / talk / words / conversation / what sb said / CL:種|种[zhong3],席[xi2],句[ju4],口[kou3],番[fan1]

It is said that ... (at the start of a narrative) / to discuss / to recount

It is said that ... (at the start of a narrative) / to discuss; to recount

to persuade

to speak / to say / to explain / to scold / to tell off / a theory (typically the last character in a compound, as in 日心說|日心说 heliocentric theory)

to speak; to talk; to say / to explain; to comment / to scold; to tell off / (bound form) theory; doctrine