The Qur'an, in 2:106, refers to the concept of naskh. However, there is a difference of opinion about the extent to which al-nasikh wa-al mansukh does in fact occur in the text of the Qur'an. The information concerning al-nasikh wa-al mansukh must be treated with great caution as, for all reports concerning the text of the Qur'an, two independent witnesses are required. Many of the examples which the scholars have drawn upon to illustrate this question (and I have quoted them for the same purpose) are based on one witness only. 'A'isha alone reported that 10 or 5 sucklings had been part of the Qur'anic recitation, and only 'Umar reported that the 'verse of stoning' had been included in the Qur'anic text. These legal rulings are not included in the Qur'an precisely because they were not considered reliable, being based on one witness only. Similarly, other examples about naskh, based on the words of Ibn 'Abbas or Mujahid alone, are to be judged by the same measure.