The relevant hadith can be found in one of the six major Sunni collections of Hadith:
It was narrated that 'Aishah said: “The Verse of stoning and of breastfeeding an adult ten times was revealed, and the paper was with me under my pillow. When the Messenger of Allah died, we were preoccupied with his death, and a tame sheep came in and ate it.”Sunan Ibn Majah, Vol. 3, Book 9, Hadith 1944 (Arabic reference: Book 9, Hadith 2020). The copy of Ibn Majah I used has designated this as a "good" (Hasan) hadith (see here).
Essentially the same story can also be found cited this way:
[Narrated 'Aisha] "The verse of the stoning and of suckling an adult ten times were revealed, and they were (written) on a paper and kept under my bed. When the messenger of Allah expired and we were preoccupied with his death, a goat entered and ate away the paper."I found it cited that way, interestingly enough, in a web page that appears to be Shi'ite, criticizing the Sunnis for their adherence to ahadith. The page argues:
Musnad Ahmad bin Hanbal. vol. 6. p. 269; Sunan Ibn Majah, p. 626; Ibn Qutbah, Tawil Mukhtalafi 'l-Hadith (Cairo: Maktaba al-Kulliyat al-Azhariyya. 1966) p. 310; As-Suyuti, ad-Durru 'l-Manthur, vol. 2. p. 13
(source)It needs no great intelligence to see that this theory of abrogation of recital cannot be of any use in such cases. If a surah or verse was recited in the life of the Prophet and then it was lost either because the reciters were killed in a battle, or because a goat devoured it or for any other reason, then the question arises: Who had the right to abrogate a Qur'anic verse after the Prophet's death? Had any other prophet come after Muhammad (peace be on him and his progeny)? That is why Sayyid al-Khu'i has said, "It is clear that the theory of abrogation of recital (naskhu 't-tilawah) is exactly the same as belief in alteration in and omission from the Qur'an."Therefore we have to strictly adhere to the well established principle that any hadith going against the Qur'an must be discarded and 'thrown to the wall' - if it cannot be reinterpreted in an acceptable way.
One downside of this particular Shi'ite approach to the hadith material is that the person will never be able to persuaded by the historical evidence that demonstrates that the Qur'an has not been perfectly preserved.
Moreover, the Shi'ite argument cited above presumes that the Qur'an was in a fixed form by the death of Mohammed. That assumption, however, is open to question. There are good reasons (such as the very hadith mentioned above) to believe that the Qur'an was not in an assembled form at least until Abu Bak'r recognized the danger arising from the fact that so many reciters of the Qur'an had died in battle during the battle of Yamama. Moreover, there is reason to believe that the form of the Qur'an created by the first caliph (Abu Bak'r) is not necessarily the same form as that provided by Uthman (the third caliph).