en_tn_lite_do_not_use/phm/01/13.md

so he could serve me for you

"so that, since you cannot be here, he might help me" or "so that he could help me in your place"

while I am in chains

Prisoners were often bound in chains. Paul was in prison when he taught Onesimus and was still in prison when he wrote this letter. Alternate translation: "while I am in prison" (See: rc://en/ta/man/translate/figs-metonymy)

for the sake of the gospel

Paul was in prison because he preached the gospel publicly. This can be stated explicitly. Alternate translation: "because I preach the gospel" (See: rc://en/ta/man/translate/figs-explicit)