In this short treatise, the 6th/12th century Baghdadi grammarian Ibn al-Ḫaššāb (d. 567/1172) presents a grammatical state-of-the-art of the scholarly research on the Hebrew word ʾāmīn in Arabic grammar. Once a foreign word has entered the Arabic language, it has to comply with its rules and fit into existing categories, both in terms of morphology and syntax. After recalling the different grammatical opinions, Ibn al-Ḫaššāb discusses the position of a few grammarians (Ṯaʿlab, Ibn Darastawayhi, ʾAbū Hilāl al-ʿAskarī, ʾAbū l-Fatḥ al-ʿAṭṭār). He then refutes ʾAbū ʿAlī l-Marzūqī and his master ʾAbū ʿAlī l-Fārisī, who devoted an exhaustive discussion to ʾāmīn in his al-Masāʾil al-Ḥalabiyyāt. The issues discussed in Ibn al-Ḫaššāb’s short treatise are the following: the part-of-speech ʾāmīn belongs to; its meaning; ʾāmīn vs. ʾamīn and ʾāmmīn; is ʾāmīn one of God’s names?