From the time of its foundation in 284/897, the Zaydi Imamate of Yemen was home to Mu?tazili ideas. During the first centuries and starting with Imam al-Hadi ila 'l-Haqq (d. 298/911), Zaydi ideology included elements very much akin to the opinions of the Baghdad School of the Mu?tazila as founded by Bishr b. al-Mu?tamir (d. 210/825). However, in the 6-7th/11-12th centuries, we see a rise in popularity of Bahshamiyya ideas, a sub-group of the Basran School of the Mu?tazila around Abu Hashim al-Jubba?i (d. 321/933). These ideas were systematized and elaborated upon by the Zaydi theologian al-Rassas (d. 584/1188), notably in his short theological summa the Kitab al-tahsil fi 'l-tawhid wal-ta?dil. This work soon gained popularity and within 30 years after his death, as three commentaries on it were written. The one whose surviving part is published here is an early witness of Yemeni Zaydi acquaintance with Ibn al-Malahimi's (d. 536/1141) works and anti-Bahshami teachings.