Muhammad Ibn Ya’qub Al-Kulaini writes:
لم يجمع القرآن كله إلا الأئمة عليهم السلام وأنهم يعلمون علمه كله

“No one collected the full Qur’an except the Imams (a.) and they have the complete knowledge of it.” [Al-Kafi, Volume 1 Page 135 Chapter 92]

Muhammad Baqir Al-Majlisi writes:

وذهب الكليني والشيخ المفيد قدس الله روحهما وجماعة إلى أن جميع القرآن عند الأئمة عليهم السلام وما في المصاحف بعضه

“The scholars Al-Kulaini and Al-Mufid, may God rest their souls and one group held the view that the complete Qur’an is with the imams (a.) and that what is in the manuscripts (Mushaf) is only a part of it.” [Mir’at-ul-Uqul, Volume 3 Page 30]

Ash-Sharif Al-Amili Al-Fatuni writes:

اعلم أن الذي يظهر من ثقة الإسلام محمد بن يعقوب الكليني طاب ثراه أنه كان يعتقد التحريف والنقصان في القرآن لأنه روى روايات كثيرة في هذا المعنى في كتاب الكافي الذي صرح في أوله بأنه كان يثق فيما رواه فيه ولم يتعرض لقدح فيها ولا ذكر معارض لها

“Know that it is clearly evident from the trustworthy one of Islam, Muhammad Ibn Ya’qub Al-Kulaini, may he rest in peace, that he believed in the falsification and removal from the Qur’an, because he narrated in this sense many traditions in the Book of Al-Kafi, about which he clearly stated in his preface that he considered as trustworthy that which he reported in it and neither condemned them in it nor mentioned anything contrary to them.” [Muqaddimat-ul-Burhan, page 83]

Muhammad Al-Faid Al-Kashani writes:

وأما اعتقاد مشايخنا رحمهم الله في ذلك فالظاهر من ثقة الإسلام محمد بن يعقوب الكليني طاب ثراه أنه كان يعتقد التحريف والنقصان في القرآن لأنه كان روى روايات في هذا المعنى في كتابه الكافي و لم يتعرض لقدح فيها مع أنه ذكر في أول الكتاب أنه كان يثق بما رواه فيه

“As for the belief of our teachers, may God rest their souls, it is clearly evident from the trustworthy one of Islam, Muhammad Ibn Ya’qub Al-Kulaini, may he rest in peace, that he believed in the falsification and removal from the Qur’an because he narrated many reports in the same sense in his book Al-Kafi and did not condemn them, mentioning in the preface of the book that he considered what he told in it as being reliable.” [As-Safi, Volume 1 Page 22]

Husain An-Nuri At-Tabarsi writes:

فاعلم أن لهم في ذلك أقوالاً مشهورها اثنان الأول وقوع التغيير والنقصان فيه، وهو مذهب الشيخ الجليل علي بن إبراهيم القمي شيخ الكليني في تفسيره صرح في أوله وملأ كتابه من أخباره مع التزامه في أوله بأن لا يذكر فيه إلا عن مشايخه وثقاته، ومذهب تلميذه ثقة الإسلام الكليني رحمه الله على ما نسبه إليه جماعة لنقله الأخبار الكثيرة الصريحة في هذا المعنى في كتاب الحجة خصوصاً في باب النكت والنتف من التنزيل وفي الروضة من غير تعرض لردها أو تأويلها

“Know that there are different opinions on this subject. The most famous of them are two, one of which says that change and removal from the Qur’an took place and this is the view of the great scholar Ali Ibn Ibrahim Al-Qumi, the teacher of Al-Kulaini, which he clearly expressed in the preface of his exegesis (Tafsir-ul-Qumi) and filled his book with reports about it, whereby he obligated himself in his introduction not to mention anything in it, except from his teachers and the trustworthy (Thiqah) and according to what one group attributed to him, the view of his disciple, the trustworthy one of Islam, Muhammad Ibn Ya’qub Al-Kulaini, may God rest his soul, on the basis of his narration of numerous traditions that clearly reflect this meaning, and especially in the book Al-Hujjah in the chapter An-Nukat Wa An-Nutaf Min At-Tanzil and in the volume Ar-Rawdah, whereby he neither rejected nor interpreted them. ” [Fasl-ul-Khitab, page 25]