[...]oquem eorum [...]
These words match part of the text of the responsory verse 'Et unumquoque eorum ibat coram facie sua' Cantus ID 007670b. This chant is sung in the Vespers for Matthaei in P-BRs Ms. 28 fol. 173v (info at http://pemdatabase.eu/musical-item/20875). However, the comparison of the music in Ms. 28 and in this fragment shows only partial correspondence between the two sources.