John Gill Commentary 1 Timothy 3:10

"And let these also first be proved; then let them serve as deacons, if they be blameless." — 1 Timothy 3:10 (ASV)

And let these also first be proved

Not that they should be tried in any part of the deacon's office, to see how capable they are of performing it; but their internal and external characters are to be looked into and examined, and if they appear to be right, then they are to be approved of, chosen and called unto, and invested with the office:

then let them use the office of a deacon ;

let them be employed and minister in the several parts and branches of that office:

being found blameless ;

not without sin, but free from any gross and enormous one; not before God, but in the sight of men; (See Gill on 1 Timothy 3:2).