“Flock” brings to mind all the shepherd imagery found in the Scriptures: the sheep gentle, defenseless, liable to stray, needing a shepherd, happy, peaceful under his care, pitiful when lost, scattered, etc. This is “God's flock” that was bought with a great price (Ac 20:28), that is exceedingly precious in His sight, a great trust placed into the hands of human shepherds who are to pattern after Yahweh, the Shepherd (Psm. 23), and Christ, the Archshepherd (1 Pet. 5:4). What shepherd could have the care of any part of God's flock and treat it carelessly!
R.C.H. Lenski