Paul earlier says it's good for the unmarried to stay single—this cross-reference provides the recommendation that the anxiety-free devotion supports.

Paul notes that marriage brings troubles he wants to spare them—this explains why the married are anxious about worldly things.

Paul states the unmarried does even better—the anxiety-free devotion of the unmarried is the reason why staying single is preferable.

Matthew 6:25-34 commands not to be anxious, seeking God's kingdom first. Paul applies this to singleness.

Philippians 4:6 directly commands not to be anxious but to pray, consistent with Paul's teaching.

Jesus commends voluntary celibacy for the kingdom—directly parallel to Paul's reasoning that the unmarried can focus entirely on the Lord's affairs.

Jesus commands not to worry about life—reinforcing Paul's wish that believers be free from anxieties to focus on the Lord.

Martha is worried and upset about many things—contrasting with Paul's desire for believers to be free from worldly anxieties to serve the Lord.