A faithful work (πιστον). Either thus or "thou makest sure," after an example in Xenophon quoted by Wettstein (ποιειν πιστα) and parallel to καινα ποιεω in Revelation 21:5. But it is not certain.

In whatsoever thou doest (ο εαν εργαση). Indefinite relative with modal εαν (=αν) and the first aorist middle subjunctive of εργαζομα. See Colossians 3:23 for both ποιεω and εργαζομα in the same sentence.

And strangers withal (κα τουτο ξενους). "And that too" (accusative of general reference as in 1. Corinthians 6:6; Philippians 1:28; Ephesians 2:8). This praise of hospitality (Romans 12:13; 1. Peter 4:9; 1. Timothy 3:2; 1. Timothy 5:10; Titus 1:8; Hebrews 13:2) shows that in 2. John 1:10 John has a peculiar case in mind.