Jesus spoke to Peter after His resurrection and before He ascended to heaven. He told Peter to feed His lambs, and feed His sheep.

"This is now the third time that Jesus shewed himself to his disciples, after that he was risen from the dead. So when they had dined, Jesus saith to Simon Peter, Simon, son of Jonas, lovest thou me more than these? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Feed my lambs.

“He saith to him again the second time, Simon, son of Jonas, lovest thou me? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Feed my sheep.

“He saith unto him the third time, Simon, son of Jonas, lovest thou me? Peter was grieved because he said unto him the third time, Lovest thou me? And he said unto him, Lord, thou knowest all things; thou knowest that I love thee. Jesus saith unto him, Feed my sheep." - John 21:14-17 KJV

Peter had received a calling from the chief Shepherd.

"Know ye that the LORD he is God: it is he that hath made us, and not we ourselves; we are his people, and the sheep of his pasture." - Psalm 100:3 KJV

Jesus died for us, redeeming us back to Himself.

"Who his own self bare our sins in his own body on the tree, that we, being dead to sins, should live unto righteousness: by whose stripes ye were healed. For ye were as sheep going astray; but are now returned unto the Shepherd and Bishop of your souls." - 1 Peter 2:24-25 KJV

Jesus appoints shepherds to oversee His flock (the church) to feed His sheep (the saints).

"Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood." - Acts 20:28 KJV

What do overseers (shepherds/pastors) feed the church?

"And I will give you pastors according to mine heart, which shall feed you with knowledge and understanding." - Jeremiah 3:15 KJV

"And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ. I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able. For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men?" - 1 Corinthians 3:1-3 KJV

"As newborn babes, desire the sincere milk of the word, that ye may grow thereby:" - 1 Peter 2:2 KJV

"For when for the time ye ought to be teachers, ye have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat. For every one that useth milk is unskilful in the word of righteousness: for he is a babe. But strong meat belongeth to them that are of full age, even those who by reason of use have their senses exercised to discern both good and evil." - Hebrews 5:12-14 KJV

"Let the elders that rule well be counted worthy of double honour, especially they who labour in the word and doctrine." - 1 Timothy 5:17 KJV

"And we beseech you, brethren, to know [“to have regard for one, cherish, pay attention to” - Thayer’s Greek Lexicon] them which labour among you, and are over you in the Lord, and admonish you; and to esteem them very highly in love for their work's sake. And be at peace among yourselves." - 1 Thessalonians 5:12-13 KJV (Another translation: “Dear brothers and sisters, honor those who are your leaders in the Lord’s work. They work hard among you and give you spiritual guidance.”)

Peter exhorted the elders (pastors).

"The elders which are among you I exhort, who am also an elder, and a witness of the sufferings of Christ, and also a partaker of the glory that shall be revealed: feed the flock of God which is among you, taking the oversight thereof, not by constraint, but willingly; not for filthy lucre, but of a ready mind; neither as being lords over God's heritage, but being ensamples to the flock. And when the chief Shepherd shall appear, ye shall receive a crown of glory that fadeth not away." - 1 Peter 5:1-4 KJV [“Elder – among Christians, those who presided over the assemblies (or churches). They did not differ at all from the bishops or overseers. Presbyters. (Thayer’s Greek Lexicon)] (Acts 14:23, Titus 1:5)