Hmm, honestly, I'm not a fan of flashbacks in books. In visual art, it makes sense to bring back the same or a similar sensation to the reader, since you have the tools at your disposal; but also, comic flashbacks offer something new by nature of existing already, because we're in the current time, and we connect the dots while reading the panels from the past.
If you just throw the same text into a reader's face in a novel, it doesn't really work like that. It can get repetitive real fast. I mean... we already read that exact same paragraph, and it doesn't really offer anything new, since it takes longer to read and hinders you from connecting the dots, so it can feel like you're just artificially adding to the word count.
Try to allude more to what happened in the past. You can trust readers that they'll know what you're talking about.
That said, if you're using a flashback? Make it something we haven't read yet, and make it a whole chapter. Something from the past that took place before we even jumped into your novel, but that's needed to explain a character's backstory. Although, even then, I'd prefer it just weaved into the story somehow. Via discussions, a small (! xD) memory flashback of a single paragraph or something. Because, let's be real: we don't really tend to remember events we forgot in succession like that.