not give someone the time of day
Ignore someone, refuse to pay the slightest attention to someone, as in He's tried to be friendly but she won't give him the time of day. This expression, first recorded in 1864, alludes to refusing even to answer the question, “What time is it?”
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.