The third juz’ of the Qur’an starts from ayah 253 of Surah Al-Baqarah (The Cow) and continues to ayah 92 of the third surah, Ali Imran (Family of Imran).
The ayat of this section were largely revealed in the early years after the migration to Madinah.
From the Virtues of Surah Ali Imran
‘Abdullah bin Buraydah narrated from his father: “I was sitting with the Prophet, peace and blessings of Allah be upon him and I heard him say…“Learn Surah Al-Baqarah and Al Imran because they are two lights that shade their people on the Day of Resurrection, just as two clouds, two spaces or two lines of (Flying) birds. The Qur’an will meet its companion in the shape of a pale-faced man on the day of Resurrection when his grave is opened. The Qur’an will ask him, ‘Do you know me?’ The man will say, ‘I do not know you.’ The Qur’an will say, ‘I am your companion, the Qur’an, which has brought you thirst during the heat and made you stay up during the night. Every merchant has his trade but this day you are behind all types of trade.’ Kingship will then be given to him in his right hand, eternal life in his left hand and the crown of grace will be placed on his head. His parents will also be granted two garments, that the people of this life could never afford. They will say, ‘Why were we granted these garments?’ It will be said, ‘Because your son was carrying the Qur’an.’ It will be said (to the reader of the Qur’an), ‘Read and ascend as long as he recites, whether reciting slowly or quickly.” (Recorded in Ahmad 5:352)
“Allah! None has the right to be worshipped but He, the Ever Living, the One Who sustains and protects all that exists. Neither slumber nor sleep overtakes Him. To Him belongs whatever is in the heavens and whatever is on the earth. Who is he that can intercede with Him except with His permission? He knows what happens to them in this world, and what will happen to them in the Hereafter. And they will never compass anything of His Knowledge except that which He wills. His Kursi extends over the heavens and the earth, and He feels no fatigue in guarding and preserving them. And he is the Most High, the Most Great.” (Surah Al-Baqarah 2:255)
“The parable of those who spend their wealth in the way of Allah, is that of a grain (of corn); it grows seven ears, and each ear has a hundred grains. Allah gives manifold increase to whom He wills, and Allah is All-Sufficient for His creatures needs, All-Knower.” (Surah Al-Baqarah 2:261)
“(Remember) when the angels said, ‘Oh Maryam! Verily Allah gives you glad tidings of a Word from Him, his name will be Al-Masih, Isa, the son of Maryam, held in honor in this world and in the Hereafter, and he will be of those near to Allah.” (Surah Ali Imran 3:45)
Near the beginning of this juz’ we find Ayat al-Kursi (2:255) which is confirmed in saheeh hadith as the greatest ayah in the Qur’an. It had tremendous virtues associated with it including praise of Allah and protection from Shaytan. You can find a detailed tafsir of this ayah here.
The remainder of Surah Al-Baqarah reminds believers that there is to be no compulsion in matters of religion. Examples are given of people who questioned Allah’s existence or were arrogant about their own importance on earth. Long passages are devoted to the subject of charity and generosity, calling people to humility and justice. It is here that usury/interest transactions are condemned, and guidelines for business transactions given. This longest chapter of the Qur’an ends with reminders about personal responsibility: that everyone is responsible for themselves in matters of faith.
The third chapter of the Qur’an Surah Ali Imran is named for the family of Imran, the father of Maryam (Mary), mother of Prophet Isa (Jesus), peace be upon them all. The chapter begins with the claim that this Qur’an confirms the messages of previous Prophets and Messengers of Allah and that it is not a new religion. One is reminded of the strict punishment facing unbelievers in the Hereafter, and the People of the Book (i.e. Jews and Christians) are called upon to recognise the truth – that this revelation is a confirmation of what came before to their own Prophets.
Towards the end of this juz’, the story of the family of Imran begins, telling us about the Prophets Zakariya (Zechariah) and his son Yayah (John), and Maryam (Mary) and the birth of her son, the Prophet Isa (Jesus).