It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Jibril (peace be upon him) taught me to recite (the Qur'an) in one harf (mode); then I kept asking him for more and he kept giving me more, until it reached seven ahruf (modes)."
Ibn Shihab (may Allah have mercy on him) said: "These seven ahruf are in fact a matter that is one (in meaning); there is no difference among them regarding the lawful and the unlawful."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Ibn Akhi al-Zuhri (may Allah have mercy on him) except al-Darawardi (may Allah have mercy on him)."
Hadith Referenceالمعجم الأوسط / باب الألف / 1792
Hadith Takhrij«أخرجه البخاري فى «صحيحه» برقم: 3219، 4991، ومسلم فى «صحيحه» برقم: 819، والبيهقي فى «السنن الكبرى» برقم: 4059، وأحمد فى «مسنده» برقم: 2412، 2761، 2905، وعبد الرزاق فى «مصنفه» برقم: 20370، والطحاوي فى «شرح مشكل الآثار» برقم: 3116، والطبراني فى «الصغير» برقم: 88»