Here scribe 2 of 𝓟 initially omitted the subordinate conjunction that but soon inserted it (there is no change in the level of ink flow for the supralinear insertion). Elsewhere, there are 20 examples where the verb pray takes a that-clause as its direct object complement, and in no instance is the that lacking. For some verbs, such as say, the that can be ellipted, as in 1 Nephi 2:11, where the that was accidentally lost when 𝓞 was copied into 𝓟: “and this they said that he had done because of the foolish imaginations of his heart”. But when the verb is pray, the that seems to be required. Scribe 2’s correction here in 𝓟 is undoubtedly the original reading.
Summary: Accept in Alma 2:28 scribe 2’s virtually immediate insertion of that in 𝓟; his correction was undoubtedly the reading of the original manuscript.