know something by heart

(verb) to have something memorized perfectly

Example Sentences:

A: Do you know all the words to The Star Spangled Banner?
B: Yes, I know it by heart.

The audience was surprised when the karaoke singer knew all of the songs by heart.

Media:

Similar idioms:

1. learn something by heart
2. heart to heart
3. wear one’s heart on one’s sleeve
4. heart goes out to someone
5. eat one’s words
6. heart is not in something
7. have one’s heart in one’s mouth
8. change of heart
9. not mince words