In an interview with Timbaland for “Rolling Stone,” Metro Boomin talked about the pros and cons of working with his longtime friend 21 Savage. He said that working with the careful rapper could be tiring at times.

“That’s something that 21 Savage and I sometimes talk about.” You said the same thing about you and Missy: “He’s the pickiest artist I’ve ever worked with when it comes to beats.” This guy has to listen to 35 or 40 beats before he can get in the room. It can be tiring: he’ll keep saying, “Next one, next one, next one.” In response, I tell them, “OK, you have to bring it on this one.” Metro said, “I’m not taking any OK shit, n***a.”

When Timbaland replied that they had done great work together, Metro agreed completely and recognized the magic they had created.

“My favorite person to work with for sure.” Going back and forth all the time will make us both mad. We make each other better, though. I’m going to cook up at home if I play him 20 beats and he doesn’t really feel them. “You need that,” he said.

“The Slaughter Tape,” 21’s first mixtape, was made by Metro. That was the start of his work on all 21 projects, in some way. Even though their relationship can get heated at times, Metro hinted earlier this year at the exciting chance of a third game in the “Savage Mode” series.

The first “Savage Mode” album came out in 2016 and had nine tracks with production from different artists, such as Southside and Zaytoven, and Future made a guest appearance. After four years, the two came back together for “Savage Mode II,” which went straight to No. 1 on the Billboard 200 and included features with Young Thug, Young Nudy, and Drake. However, Drake probably won’t be on the much-anticipated third part because he is still fighting with Metro.