A.T. Robertson Commentary 1 Thessalonians 5:11

"Wherefore exhort one another, and build each other up, even as also ye do." — 1 Thessalonians 5:11 (ASV)

Build each other up (οικοδομειτε εις τον ενα). Literally, build ye, one the one (εις nominative in partitive apposition with unexpressed υμεις subject of οικοδομειτε. Then τον ενα the accusative in partitive apposition with the unexpressed εαυτους or αλληλους. See the same idiom in 1 Corinthians 4:6 one in behalf of the one , εις υπερ του ενος. Build is a favourite Pauline metaphor.