Peter speaks of one “flock”; the word is singular (and we have no idea how many “sheep” were in this flock). That is because the chief Shepherd (1 Peter 5:4) has one people saved by one blood, united by one faith, embracing one Lord, one faith, one baptism, one God and Father (Ephesians 4:4–6).
2 shepherd the flock of God that is among you, exercising oversight, not under compulsion, but willingly, as God would have you; not for shameful gain, but eagerly;