Choosing the good part

Reading 2 Nephi 2:30,

I have chosen the good part, according to the words of the prophet.

I was left wondering which prophet Lehi is talking about. I can't find any passage in the Old Testament this would point to. The only other place in the scriptures talking about choosing the good part is found in Luke 10:42 in the well-known story of Martha and Mary

But one thing is needful: and Mary hath chosen that good part, which shall not be taken away from her.

I noticed another similarity between these two accounts in the preceding verses. The only thing we are told about Mary in this story is found in Luke 10:39

And she had a sister called Mary, which also sat at Jesus’ feet, and heard his word.

In 2 Nephi 2:28

And now, my sons, I would that ye should look to the great Mediator, and hearken unto his great commandments; and be faithful unto his words, and choose eternal life

This verse conveys the idea about hearkening unto his words and choosing eternal life. Choosing eternal life is choosing the good part. But it is preceded by hearkening unto his words, the same thing Mary was described doing before Jesus commended her for choosing the good part.

This could all just be a coincidence. But the fact that Lehi refers to the words of a specific unnamed prophet, which is clearly not a reference to Luke, makes me wonder if both Lehi and Jesus are referring to an extra-biblical source, perhaps found on the brass plates.

In any case, it is interesting to find a common message in two seemingly very unrelated accounts of scripture. As Peter said in John 6:68: "thou hast the words of eternal life". Consequently, when we hear the word of God, eternal life is presented to us but we must choose it. This is the good part that Mary and Lehi chose. The alternative is the 'bad part', disobeying and thereby choosing death.