(22) باب أُنْزِلَ الْقُرْآنُ عَلَى سَبْعَةِ أَحْرُفٍ
Al-Zuhri said:
These modes of reading aimed at the same point, not different in respect of lawful and unlawful.
Reference: Sunan Abi Dawud 1476
In-book reference: Book 8, Hadith 61
English translation: Book 8, Hadith 1471