hang on someone's words - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Listen very attentively to someone. For example, You don't need to hang on his words—just remember the gist of it. It is also put as hang on to every word, as in Whenever Mother read their favorite book to them, the children hung on to every word.