After Simpson shared a shirtless black-and-white pic of himself on Instagram, Bieber took to the comments section to praise the fellow pop singer.
"Ur body is a wonderland," Bieber commented, adding in a second note, "Double date?"
"Text me," Simpson responded.
Earlier this week, Simpson visited Cyrus in the hospital when she was sick with tonsillitis. While there, Simpson serenaded Cyrus with a song he wrote for her, while Cyrus dubbed the Australian singer her "BF."
Despite the frequent sightings between the pair, a source recently told ET that Cyrus and Simpson have "no plans to start dating each other exclusively."
"Miley and Cody have been friends for years. They have hooked up in the past... They both just want to have fun and are open and honest with each other about that," the source said. "Miley and Cody talk to each other about everything. They are very close and feel comfortable sharing details with each other about their lives."
"Cody and Miley are in the same social circle and both have firsthand knowledge of what it’s like constantly being in the public eye," the source added. "He is safe to her because they have been friends for years and she feels no pressure at all."
Watch the video below for more on Simpson and Cyrus.