"Big Poppa," songs that Biggie resisted recording—to increase radio appeal and sales, yet placed harder songs as their B sides. The "Big Poppa" B side, "Warning," an album track, thus in practice a "double A side," relies on the instrumental of Isaac Hayes's cover version of "Walk on By," and casts Biggie suspecting that members of his own circle will set up him up for a robbery. Each of the two songs received its own music video."The Notorious B.I.G.—'Warning' (official music video)", The Notorious B.I.G. "Official Artist Channel" @ YouTube, 6 Sep 2011. Mixtape version An underground "Who Shot Ya" differing—but same instrumental—was released in 1995 before the single. Amid lore of this mixtape version, some speculated that it was a myth. (In 2017, DJ EFN casually ventured that he may have had an underground issue on vinyl in a white sleeve, as used by DJs, before December 1994.) In 2014, when the mixtape "Who Shot Ya" was traced to DJ S&S, a renowned issuer of New York mixtapes in the 1990s, its original audio was publicized. Like a mixtape track, it is only two minutes long—one Biggie verse, 24 bars, then one Keith Murray verse, 23 bars, amid "hype man" Puffy tersely yelling announcements—but the verses are longer than the standard 16 bars. In 2004, Brooklyn rapper Shawn "Jay-Z" Carter recollected, about the mixtape, "I've heard songs I like, but the last time I remember being truly, truly inspired was when I heard 'Who Shot Ya.' " One night, Kareem "Biggs" Burke, cofounder of Jay-Z's label, Roc-A-Fella Records, drew him to Harlem's 125 Street, entered his car, inserted the tape, and fled. Jay-Z reflects, "He knew that if I heard 'Who Shot Ya?,' it's going to inspire me to make songs even hotter. But that song, it was so crazy. It just had an effect on everybody. The world stopped when he dropped 'Who Shot Ya?' " On Jay-Z's debut June 1996 album's track "Brooklyn's Finest," guest Biggie includes the phrase who shot ya and the word warning. Single version Closing the week of February 25, 1995, the "Big Poppa/Warning" single—released December 5, 1994—had spent six weeks, including five weeks at No. 1, on Billboard's Hot Rap Singles chart. The single entered the main popular songs chart, the Billboard Hot 100, the week ending January 14 and, enduring 24 weeks, peaked at No. 6 on March 18. Yet on