Is it a good idea to delay information?

my characters have a talk before they’re killed, and that information that they talk about is going to be important later on in the novel when my main characters learn about the man they speak of. I don’t want to give too much away, as i want the main character to figure it out and the reader to go along the journey but is this a bad idea? will it confuse or frustrate the reader if i don’t explain my deceased characters conversation while it happens? or should i be vague about it or give the smallest and most necessary details without revealing too much?