If thou faint in the day of adversity, thy strength is small. If thou faint - If thou give way to discouragement and despair in the day of adversity - time of trial or temptation.
Thy strength is small - צר כחכה tsar cochachah, thy strength is contracted. So the old MS. Bible excellently: Gif sliden thou dispeire, in the dai of anguyfs, schal be made litil thy strengthe. In times of trial we should endeavor to be doubly courageous; when a man loses his courage, his strength avails him nothing.