The 5th phrase of the Lament of Akallabêth (SD/247). The subject azrîya is the subjective plural of azra “sea”. Judging by the glosses, the verbal prefix du most likely indicates the optative or subjunctive moods (see those entries for discussion). The verb form phursâ resembles the aorist tense of the verb phurus-, except that the long â is unusual. Perhaps this variation is because the verb is actually in an infinitive form, though Andreas Moehn instead suggested the verb stem may be a derived verb ✱phursâ- (EotAL/PHUR). The last word akhâsada is the word akhâs “chasm” with the prepositional suffix -ada “towards, into”.
The gloss of the manuscript version was “that seas should gush into Chasm” (VT24/12). This gloss seems to indicate that this sentence might actually be a subordinate phrase of the preceding sentence Bârim an-Adûn yurahtam dâira sâibêth-mâ Êruvô “Lords of the West, they broke the Earth with assent from Eru”. This would fit well with its use of the optative/subjunctive mood, so that this phrase gives reason why the Valar broke the Earth (to sink Númenor). However, both the manuscript and typescript versions separated the two sentences with an ellipsis “...”, indicating that they are separate sentences.
A verbal prefix in the sentence azrîya du-phursâ akhâsada and translated as either “so-as” (SD/247) or “should” (VT24/12). It almost certainly indicates some verb-mood. Most authors have suggested it indicates the subjunctive mood based on its glosses (VSH/25, LGtAG, AL/Adûnaic). I think it could also be the optative mood, since in the first draft versions of the sentence the word was nai, clearly related to Q. nai “maybe, may it be that” used for the expression of a wish. Since it appears in only a single example, we don’t have enough information to be sure.