As for al-Taḥbīr, it is possible that he simply reproduced those citations from it, and Allah knows best.

Although these quotations are not found in the copy that has reached us, they still prove that Ibn Rajab authored a book entitled Tafsīr al-Fātiḥa. Their absence from the extant manuscript is probably—Allah knows best—because what we possess is only a fragment of the work, as noted earlier; the missing passages would therefore be in the portion that was never transcribed. Allah knows best.

Fourth: The scholarly style of Ḥāfiẓ Ibn Rajab is plainly evident in this treatise. He is careful in selecting hadiths and discusses them according to the methodology of the early hadith masters. He pays close attention to the statements of the salaf, and he also quotes Shaykh al-Islām Ibn Taymiyyah as well as Ibn Taymiyyah’s student—and Ibn Rajab’s own teacher—the eminent Ibn al-Qayyim.

Title of the Work
Ḥāfiẓ Ibn Rajab did not state that he gave this book a specific title; he merely began with the words, “A section on the exegesis of Sūrah al-Fātiḥa.” Yet the flyleaf of the manuscript carries the following inscription:

“Tafsīr al-Fātiḥa by Shaykh Zayn al-Dīn Abū al-Faraj ʿAbd al-Raḥmān ibn Aḥmad ibn Rajab al-Ḥanbalī—may Allah sanctify his soul and illuminate his grave.”