What is the meaning of [Men strain at gnats and swallow camels]

This is hypocrisy, the behaviour of those who speak loudly against small
offences while committing, much greater offences at the same time. Jesus says
to the scribes and Pharisees : ‘Ye blind guides, which strain at a gnat, and
swallow a camel. ‘ To ‘strain a gnat ‘ is to filter the wine after finding a
gnat in it.