1 Corinthians 15:58--The Work of the Lord

I find it intriguing that the apostle Paul does not explicitly define the Lord's work in 1 Cor. 15:58. Another question I've long had about this verse is how do we know the Lord, in this case, is Jehovah. Could it be Jesus Christ instead, whom God made Kurios? Here's what others have written about 15:58.

NIV Cultural Backgrounds Study Bible:

15:58 your labor in the Lord is not in vain. Speakers and writers often concluded a work or a section with a summary statement (cf. the risk of acting in vain in vv. 2,14,17); conclusions sometimes offered exhortations. Many people who believed in future judgment thought that those who did not (such as Sadducees or Epicureans) lacked reasons to behave morally. In view of the future resurrection of the body, which will last forever, believers should live wholly for Christ (cf. 6:13 – 14).

Expositor's Greek Testament:

περισσεύοντες κ.τ.λ. adds the positive to the foregoing negative side of the injunction: “abounding (overflowing: see parls.) in the work of the Lord always”. τ. ἔργον τ. Κυρίου (cf. 1 Corinthians 9:1; Colossians 3:23 f., Matthew 21:28, Mark 13:34) is “the work” which “the Lord” prescribes, while “the work of God” (Romans 14:20 : cf. Romans 3:9 above) is “the work” which “God” does: contrast 1 Corinthians 12:5-6 above.—“Knowing (as you do) that your toil is not empty in the Lord.” εἰδότες implies assured knowledge, such as springs from the confirmation of faith given in this chap. On κόπος, see note to 1 Corinthians 3:8; and on κενός, 1 Corinthians 15:14 : the “toil” is “empty” which is spent on illusion; “ce n’est pas là une activité d’apparat, accomplie dans le néant, comme si souvent le travail terrestre, mais un sérieux labeur, accompli dans la sphère de l’éternelle réalité” (Gd[2590]); hence the pr[2591] ἐστὶν rather than ἔσται.—ἐν Κυρίῳ: in the sphere of Christ’s authority, wrought under His headship, which supplies the basis of all Christian relations and duties; cf. 1 Corinthians 15:36, 1 Corinthians 4:17, 1 Corinthians 7:22, etc.

Joseph A. Fitzmyer, First Corinthians, page 608:

The phrase to ergon tou kyriou, “the work of the Lord,” will appear again in 16:10 as a way of expressing the evangelical ministry, in which both Paul and Timothy are engaged. Cf. Phil 3:30 [sic], where Epaphroditus’s ministry is characterized as “the work of Christ.” In each case, the subj. gen. expresses the one who has assigned the task to Paul, Timothy, or Epaphroditus. Here the phrase has a broader comprehension, denoting all that Corinthian Christians do in their service of the Lord, and the gen. is rather objective. Such service is more important than all disputatious denials of the resurrection of the dead or queries about its nature; that is why Paul recommends it to them.

Note the variants for Philippians 2:30 (not 3:30):
https://www.stepbible.org/?q=version=VarApp|reference=Phil.2.30&options=GNHVU