Shulchan Arukh Orach Chayim · Siman 116

English

Commentary on the the Blessing "Heal us". Containing 1 Se'if: "Heal us, O God, and we shall be healed..." Even though a verse that is written in the singular may not be modified to the plural [i.e. like the beginning words of this blessing which in Jeremiah 17:14 is written in the singular "heal me"] - this applies in the case when it was intended to be recited [as a verse], but when one says it in the context of a prayer or a request, it is permitted [to modify it]. Gloss: Nevertheless, if one says an entire psalm, it is forbidden to alter it from singular to plural or vice versa. (Tur and the Rosh on the chapter "Hakoreh Omed" [Talmud Megillah 4] in the name of the Ri]