The reference here to the friends (awliya') and chosen ones (asfiya') is the Mawla's followers (Shi'a) who hold high ranks.

Al-Mufaddal, peace comes from him, said: I asked my Mawla Ja'far Al-Sadiq, may his glory be exalted, about His saying: {And We ransomed him with a great sacrifice}. He said: 'He is Al-Husayn in the time of Abraham in the esoteric (Batin). Al-Hasan was Isaac, and Al-Husayn was Ishmael.' I asked: 'My Master, tell me about the story of the sacrifice.' He said: 'O Mufaddal, do you not see that the Messiah is more favored by God than all the Prophets and Messengers, and He made the killing and crucifixion appear upon Himself? But when God wills to manifest a matter, He manifests a part of it so that the outer (Zahir) may lead to its inner (Batin), and the part may lead to the whole. Do not consider God's power too vast to comprehend, and do not cut short God's greatness in His Prophets, chosen ones, and Successors, that He would make them taste the heat of iron. Al-Husayn was more honored by God than that He should make Him taste the heat of iron or make Him taste killing at the hands of the disbelievers. Indeed, God possesses a gentle grace in arranging what He gently grants His friends, saving them from their enemies, and destroying His enemies and the enemies of His friends with the most compelling. He is Just and does not wrong, and Forbearing and does not tire. God did to Al-Husayn what He did not do to the Messiah, nor to Zechariah, nor to John (Yahya), nor to any of the Prophets. The sacrifice was apparently for Ishmael, who was ransomed with a great sacrifice, which is, by God, Al-Husayn Himself, in His very essence, name, and lineage. There is no difference between them, as if they were one. He was apparently sacrificed more than a thousand times according to the imagination of the people of disbelief and misguidance. His example is like the example of the Messiah. Do you not see that God says and reports the saying of the Jews who claim they killed Him: {And they said, 'We have killed the Messiah, Jesus son of Mary, the Messenger of God.' But they neither killed him nor crucified him, but it was made to resemble for them. Indeed, those who differ over it are in doubt concerning it. They have no knowledge of it except the following of assumption. They did not kill him for certain, rather God raised him to Himself}. This characteristic is the characteristic of the killing of the Prophets, Successors, and friends (Awliya'). And God does what He wills.