The fourth proof is contained in the directive of the Imams of Ahl ul-Bayt (‘a) to read a complete Surah in the first two raka’ats of every obligatory prayer, after the Surah of al Fatihah. And they allowed to divide a Surah or more in the case of Salat ul ayat (prayers which become incumbent due to natural phenomena like eclipses or earthquakes etc.), the details of which can be found in its place in Fiqh.
Obviously, these laws are established parts of Shari’ah ever since the prayers became obligatory, and they were not prompted by taqiyyah or dissimulation. For those who hold that Tahrif or interpolation has taken place in the Qur’an, it is important that they do not recite those Surahs which they consider to have been tampered with, because restraint is the only sure alternative in the case of doubt. Their excuse that since a complete, unvaried Surah is not available, therefore they have to accept whatever is available, cannot be accepted because that would apply only if they believe that all the Surahs have been interpolated. Since there is a Surah, like Surah of Ikhlas, which has remained intact, they would have to resort to its recitation excluding the others.
The directive by the Imams of Ahl ul-Bayt (‘a) would not be of any help to them as any authority, because the very fact that the Imams have permitted and directed to read a complete Surah from the existing Qur’an indicates satisfactorily that there has been no Tahrif whatsoever. Otherwise, a Muslim unable to fulfil the, required condition of reciting a complete Surah after al‑Fatihah would have to be exempted from the obligatory prayers. We find that the Imams have directed us to read the Surahs of Ikhlas and Qadr, recommended for every prayer. Since the question of taqiyyah was never relevant here, the recommendation and directive to read these two complete Surahs extends to all other Surahs of the Qur’an.
A pretext that the obligation to recite a complete Surah has been abrogated in the favour of reading whatever is currently available in the present Qur’an is unacceptable, and I do not think the believers in interpolation would seek refuge under it. The fact is that no abrogation of this type could lave occurred after the Prophet (‘s). Some scholars have hypothetically discussed the possibility or otherwise of such an abrogation, but we are not concerned with those hypotheses here.
In short, there is no doubt that the Imams of Ahl ul-Bayt (‘a) have directed to recite the Surahs from the Qur’an we have among us in the prayers. This ordinance has no room for taqiyyah either. One has to believe that this was also the established directive given by the Prophet (‘s) himself. It could not be a later development because that would imply an abrogation ‑ and no abrogation ever occurred after the Prophet (‘s), in spite of the hypothetical possibility. When it is established beyond doubt that the ordinance of reciting complete Surahs existed in the days of the Prophet (‘s), it follows that there has been no Tahrif. This is evidenced in every law of Shari’ah, and it has been successfully applied by the Ahl ul-Bayt (‘a) to their directive to recite a complete Surah or a complete ayah.