Musnad Ahmad 1034:34

Waki’ narrated to us, from Sufyan, from Ibrahim ibn al-Muhajir, from Rib’i ibn Hirash, who said: He who does not lie to me narrated to me—meaning Hudhayfah—who said: "The Prophet (ﷺ) met Jibril while he was at the stones of al-Mira’. He said: 'Your nation recites the Quran according to seven ahruf (modes/dialects). So whoever among them recites according to a harf, let him recite as he was taught, and let him not turn away from it.'" My father said: And Ibn Mahdi said: "Indeed, among your nation is the weak one, so whoever recites according to a harf, let him not shift from it to another out of aversion to it."