Show ingratitude, turn against a benefactor. For example, The college gave me a scholarship, so I shouldn't bite the hand that feeds me and criticize its hiring policies. Used about 600 b.c. by the Greek poet Sappho, this metaphor of a dog biting its master was first recorded in English in 1711.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.