hang on someone's words
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.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.