During the “Forceback” scene
When Rey, Han, Chewie, and Finn go to Takodana to meet Maz Kanata, Rey is called to something through the Force. She follows the call to a mysterious chest in Maz’s basement and opens it. In the box is Luke’s old lightsaber and when she reaches it, she has what director J.J. Abrams’ calls a “Forceback,” which is just basically a flashback through the Force.
She sees images of her parents leaving her, Luke and Vader’s fight, and visions of Luke’s academy burning. However, it is very odd she doesn’t see any images of Anakin. He was the one who built the lightsaber and used it the most. It was with him when he turned to the Dark Side and in his battle with Obi-Wan on Mustafar.
Why Anakin wasn’t included in these “Forcebacks” is very odd. It would’ve made a ton of sense to see scenes from his and Obi-Wan’s fight on Mustafar. Hearing a quick, “You were my brother, Anakin, and I loved you,” would’ve been a very emotional addition to this scene, and made sense if this lightsaber was showing Rey all it has been through.
Storywise it makes more sense to include scenes from the prequels than it does to not include them. The reason they were left out, could’ve been due to a request from Disney to distance the new trilogy from the prequels as much as possible.