Luke 10:42

One thing is needful. Compare ch. 18:22, “Yet lackest thou one thing.” Martha was diligent, prompt, and energetic, but lacked the calm, devotional spirit of her sister Mary (see DA 525). She had not learned the lesson set forth in Matt. 6:33, of making the kingdom of God first in her interests and endeavors, and of according material things a subordinate role (see on vs. 24-34).

That good part. As a result of her own experiences Mary had learned the lesson her sister Martha yet needed to learn (see Additional Note on Chapter 7). Some consider the expression “good part” to be an adroit play on words, by which Jesus makes a reference to the best dish on the table. “The good part,” the “one thing” needful for Martha, was a deeper concern for a knowledge of the kingdom of heaven.

Not be taken away. The material things in which Martha interested herself could be taken away (see chs. 12:13-21; 16:25, 26). Mary was storing up “treasure in the heavens that faileth not, where no thief approacheth, neither moth corrupteth” (Luke 12:33; see on Matt. 6:19-21).