Joseph has a lengthy historical expansion which covers the entire book. Joseph describes his initial imprisonment (chapter 1) and spends chapters 2-9 describing the traps set by the “Egyptian woman” trying to coax him in a sexual affair. She uses promises (3:2-3), flattery (4:1), threats (5:1), and food “mixed with enchantments (6:1). Joseph deals with these temptations through prayer and fasting (3:6, 4:7-8, 6:7-8). When Joseph is arrested he is put in chains and is whipped, yet he glorifies God and praises him (cf. Acts 16, Paul and Silas praise God from the Philippian prison).
This would have been of interest for the early church, since Joseph goes joyfully to his persecution and possible martyrdom. Joseph is a model of how to be a good Christian martyr. Even in prison the woman still harasses him, promising to get him out of prison if he sleeps with her (chapter 9). Chapter 10 is a moral exhortation based on this long sequence to practice patience, prayer and fasting. God loves self-control (10:2); everyone that honors the Law of the Lord is honored by him (11:1).
Chapters 12-16 tell an apocryphal story concerning how Joseph was sold into slavery in the first place. He is beaten harshly by the Ishmaelites who do not know if he is a slave or a freeman. Joseph endures this treatment, it appears, so as not to get his brothers into trouble for selling him into slavery. He is bought by a trader who treats him harshly, but the man’s wife talks her husband into treating Joseph with respect. The story is used in chapters 17-19 to show that if one endures suffering, especially so as to protect others, then the Lord is “delighted” and will protect him and prosper him (18:1-4). Even when Joseph had the opportunity to get revenge on his brothers, he did not take it (17:4-8). Joseph is presented as an archetypical righteous man in this Old Testament expansion. His extraordinary godliness will be the subject of Joseph and Asenath, another Old Testament expansion.
Chapter 19 is a mini-apocalypse which has been heavily edited by a Christian hand (Verse 3-7 are preserved only in Armenian, and the Armenian 8-12 is very different than the Greek, OTP 1:824, note b). In 19:1-2 Joseph has a vision of twelve stags grazing. Nine of these were “scattered” over the whole earth, as were the other three. This is obviously a reference to the twelve tribe of Israel in dispersion; the three tribes which separate are likely Judah, Benjamin and Levi.
Skipping to verse 8-12, a virgin is born from Judah, from whom comes a spotless lamb. The lamb conquers and destroys his enemies (verses 8-9). Verses 10-12 are very much as we have read in the rest of the testaments, honor Judah and Levi since from them will arise, not just “salvation for Israel,” but the Lamb of God who will take away the sins of the world (cf. John 1:29). The kingdom this lamb establishes will never end. The Armenian adds verses 3-7, an apocalyptic vision with various animals which represent political or historical elements. It is possible this is the original form of the text and these animals are intended to represent Maccabean rulers (OTP 1:824, note c).
The death notice in chapter 20 includes a prediction that the Egyptians will oppress the Jews and a request to buy Asenath near Rachel at the hippodrome. This is an indication the author was familiar with the LXX, since in Genesis 48:7 MT Rachel is buried on the way to Ephrath, but in the LXX it is “hippodromes.”