Wel bet is roten appul out of hoord
Than that it rotie al the remenaunt.
Modern English:
A rotten apple’s better thrown away
Before it spoils the barrel.
– Geoffrey Chaucer
The Canterbury Tales, The Cook’s Tale. This is one of the earliest documented versions of the proverb about one bad apple spoiling the barrel. The bad apple in this case is the apprentice cook Perkin, who likes partying so much that he abandons his duties if there is a party close by, so his master decides to be get rid of him.