The original manuscript (which is not extant here) probably had behold. The supralinear behold was inserted with heavier ink flow in the printer’s manuscript. Oliver Cowdery probably made this correction when he proofed 𝓟 against 𝓞. A similar supralinear insertion with the same heavy ink flow is found three lines later on this same page of 𝓟:
Since behold is not necessary, we can be confident that it was in 𝓞. There are numerous examples of “for behold” in the original text (261 times, including this one).
Summary: Maintain in 2 Nephi 30:1 the corrected reading in 𝓟, which reads “for behold” at the beginning of a clause.