Sayyiduna Umar bin Khattab (may Allah be pleased with him) narrates that I heard Hisham bin Hakim bin Hizam (may Allah be pleased with him) reciting Surah Al-Furqan in a different recitation from mine, although my recitation was taught to me by the Messenger of Allah (peace and blessings be upon him) himself. I was about to hasten to quarrel with him, but I gave him respite until he finished the prayer. Then I brought him to the Messenger of Allah (peace and blessings be upon him) and said: O Messenger of Allah! I heard him reciting Surah Al-Furqan in a recitation different from the one you taught me. The Messenger of Allah (peace and blessings be upon him) said to him: "Recite." He recited in the same way as I had heard him. The Prophet (peace and blessings be upon him) said: "It was revealed in this way." Then he said to me: "Recite." I recited, and he said: "It was revealed in this way also. Indeed, this Qur'an has been revealed upon seven modes, so recite whichever of them is easy for you."
Hadith Referenceالسنن المأثورة / باب ما جاء في الصلاة على الراحلة / 102
Hadith Takhrijصحیح بخاری، الخصومات، باب كلام الخصوم بعضهم في بعض، رقم : 2419، صحیح مسلم، المساجد ومواضع الصلاة، باب بيان ان القرآن ..... الخ، رقم : 818۔