10. Night and day—(See on 1Th 2:9). Night is the season for the saint's holiest meditations and prayers (2Ti 1:3).
praying—connected with, "we joy"; we joy while we pray; or else as Alford, What thanks can we render to God while we pray? The Greek implies a beseeching request.
exceedingly—literally, "more than exceeding abundantly" (compare Eph 3:20).
that which is lacking—Even the Thessalonians had points in which they needed improvement [Bengel], (Lu 17:5). Their doctrinal views as to the nearness of Christ's coming, and as to the state of those who had fallen asleep, and their practice in some points, needed correction (1Th 4:1-9). Paul's method was to begin by commending what was praiseworthy, and then to correct what was amiss; a good pattern to all admonishers of others.