The Proof for the Prohibition of Iltizaam-e-I`tiqaadi
The proof for this appears in the Qur`aan Majeed, Sunnat and Kitaabs of Fiqh:
As for The Kitaab, the statement of Allaah Ta`ala, "Do not make Haraam the pure things which Allaah had made Halaal for you, and do not exceed the bounds", together with its sabab-e-nuzool (reason of revelation).
As for the Sunnat, is the Hadith of Ibn Mas`ood (رضي الله عنه) where people only turn to their right side (after Salaat).
And as for Fiqh, as they have mentioned the abomination of stipulating and fixing a specific Surah.
And Allaah Ta`ala knows best. [page 470]
[The Principles And Codes Of Law In Hanafi Fiqh, Moulana Ashraf Ali Tahaanwi رحمه الله]