en_tn/1ti/05/21.md

the chosen angels

This means the angels whom God and Jesus have chosen to serve them in a special way.

to keep these commands without partiality, and to do nothing out of favoritism

The words "partiality" and "favoritism" mean basically the same thing. Paul is emphasizing that Timothy must judge honestly and be fair to everyone. Alternate translation: "to keep these rules without being partial or showing favor to anyone" (See: rc://en/ta/man/translate/figs-doublet)

these commands

The phrase "these commands" could refer to 1) the rules Paul just told Timothy or 2) the rules Paul is about to tell Timothy.