Compare Jesus Ben Sira, Sirach 48:10 and 4Q521 5:2

“... Puech rightly recognizes in the last line a citation of Mai 3:24 (4:6), which says that God will send Elijah before the day of the Lord and "he will turn the hearts of fathers to their children and the hearts of children to their fa­ thers." 1 0 1 The same phrase is cited in the praise of Elijah in Sir 48:10. [...] Puech's conclusion from these parallels is that the speaker in this fragment, and the subject of the verb "I will liberate," is the new Elijah (Mai 3:24 [4:6]) or the new Moses (3:22 [4:4]). Puech distinguishes this figure from the messiah, who is referred to in the third person in other fragments. 1 0 2 The only other occurrence of a verb in the first person in 4Q521 is in the long passage from fragments 2 ii+4 cited above: "forever will I cleave to [those who] hope." In that case the subject is presumably the author of the composition. Puech suggests that in fragment 2 iii the subject is also the author of the text "in a sort of vision," perhaps the Teacher of Righteous­ ness speaking as the new Elijah or new Moses. The messiah in 4Q521, then, is "clearly the kingly messiah, whom the prophet announces." 1 0 3 In Puech's view, 4Q521 conforms to the expectation of a prophet and the messiahs of Aaron and Israel, which he takes to be consistent in the Scrolls. [...] It is unlikely, however, that the Teacher or any other human author would claim in the first person to be the liberator. The most plausible sub­ ject in this fragment is surely God, just as God is the subject who sets cap­ tives free in fragment 2 ii (which begins with the reference to the messiah whom heaven and earth will obey). It is true that the first person referent in fragment 2 ii+4 is the human author, but it is not unusual to have vacil­ lation between God and a human author in a prophetic text. Isaiah 61 pro­ vides a relevant example. ...”