Job Prays for His Accusers and the Golden Vials of the Prayers of Saints
Old Testament: Job 42:8
Take unto you therefore seven oxen, and seven rams, and go to my servant Job, and offer for yourselves a holocaust: and my servant Job shall pray for you: his face I will accept, that folly be not imputed to you: for you have not spoken right things before me, as my servant Job hath.
Old Testament, also: Job 42:10
The Lord also was turned at the penance of Job, when he prayed for his friends. And the Lord gave Job twice as much as he had before.
New Testament: Apocalypse 5:8
And when he had opened the book, the four living creatures, and the four and twenty ancients fell down before the Lamb, having every one of them harps, and golden vials full of odours, which are the prayers of saints:
The connection
God does not forgive the three friends directly. He could, and instead He routes their pardon through the very man they spent the whole book accusing, and He says why: his face I will accept. The sacrifice is theirs, seven oxen and seven rams offered by their own hands, but it is not the sacrifice that secures the outcome; it is Job praying over it. Nothing in the arrangement is necessary. God needs no intermediary to pardon Eliphaz, and Job has no power of his own to grant it. What the text records is a free divine choice to accept one man's face on behalf of others, and to make that acceptance the channel through which mercy actually arrives. The Apocalypse shows the same arrangement no longer improvised for one occasion but permanent and furnished. The prayers of saints are not described as reaching God unaided; they are held in golden vials, carried by the living creatures and the ancients, and offered before the Lamb as incense. Job stood on the earth holding up men who had wronged him. The ancients hold up the prayers of the whole Church, and the acceptance is now grounded not in any creature's righteousness but in the Lamb standing as though slain in the middle of the throne.
Moral sense
The prayer God accepted was offered for the men who had spent the entire book misjudging him, and it was in praying for them that Job himself was restored. Intercession for those who wronged you is not an advanced form of charity kept for the strong; in Job it is the ordinary door out of your own affliction.
Anagogical sense
What Job did once, standing between his accusers and God, is the settled work of heaven, where the prayers of the whole Church are gathered, carried, and offered before the Lamb without interruption.
The Fathers
St Gregory the Great, Moralia in Job, Book XXXV, sect. 12, reading Job's intercession for his friends as a figure of the Church's: "I accept not your sacrifices, I hear not the words of your petitions, except through the intercession of her, whose words of confession concerning Me I acknowledge true."
Warrant
Apocalypse 5:8 does not cite Job 42:8, and neither passage names the other. The link is one of pattern rather than quotation: a righteous man whose prayer God chooses to accept on behalf of others, and a heavenly court where the prayers of saints are gathered and offered. Gregory the Great does read Job 42:8 as intercessory in a corporate sense, taking Job as a figure of the Church through whom the sacrifices of the returning are accepted, which supports the reading of the Old Testament verse but is not itself a comment on the Apocalypse.
Catechism of the Catholic Church, paragraph 2683.