Abdullah bin Abi Bakr (may Allah have mercy on him) narrates from his father that in the letter of the Prophet (peace and blessings be upon him) to Amr bin Hazm (may Allah be pleased with him) there was: "Touch the Qur'an only while in a state of ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 408
Hadith Gradingمحدثین:صحيح لغيرهٖ
Hadith Takhrij«صحيح لغيرهٖ۔ أخرجه الدار قطني 1/121»
Abu Bakr bin Muhammad bin Amr bin Hazm narrates from his father, from his grandfather, from the Prophet (peace and blessings be upon him) that he (peace and blessings be upon him) wrote a letter to the people of Yemen in which the obligatory duties, the Sunnahs and the blood-monies were mentioned, and sent it with Sayyiduna Amr bin Hazm (may Allah be pleased with him). Then he mentioned the long hadith, in which there was also: "None should touch the Qur'an except one in a state of ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 409
Hadith Gradingمحدثین:صحيح لغيرهٖ
Hadith Takhrij«صحيح لغيرهٖ۔ أخرجه الدار قطني 1/121»
Sulayman bin Musa (may Allah have mercy on him) said: I heard Salim (may Allah have mercy on him) narrating from his father (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "None should touch the Qur'an except one in a state of ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 410
Mus'ab bin Sa'd narrated: I used to hold the mushaf for Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with him), and (one day) I scratched myself. Sayyiduna Sa'd (may Allah be pleased with him) said: Perhaps you touched your private part? I said: Yes! He said: Get up and perform ablution. So I got up, performed ablution, then came back.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 411
Abd al-Rahman bin Yazid (may Allah have mercy on him) said: We were with Salman (may Allah be pleased with him); he came back after relieving himself, and I said: "O Abu Abdullah! If only you had performed ablution, perhaps we would ask you about some verses." He said: "I am not touching it (the Qur'an)." Then he said: "None touch it except the purified" [Surah al-Waqi'ah: 79]. Then he recited to us whatever we wished.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 412
Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that Sayyiduna Umar (may Allah be pleased with him) went out with his sword hanging at his side. Then he narrated the hadith, in which it is mentioned that it was said to him: Your brother-in-law and your sister have turned away from the religion and have abandoned your religion. So Sayyiduna Umar (may Allah be pleased with him) walked until he came to them, and with them was a man from the Muhajirun called Khabbab (may Allah be pleased with him); they were reciting Surah Ta Ha. Umar (may Allah be pleased with him) said: Give me the book that you have, so that I may read it. And Sayyiduna Umar (may Allah be pleased with him) used to read books. His sister said: You are impure, "None touch it except the purified" [Surah al-Waqi'ah: 79]; go and take a ritual bath or perform ablution. The narrator says: Sayyiduna Umar (may Allah be pleased with him) got up, performed ablution, took the book and recited Surah Ta Ha. This hadith has many supporting narrations.
(b) It is the view of the seven jurists of the people of Madinah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 413