Hizb 1 opens the Quran with Al-Fatiha in full, the seven verse prayer for guidance repeated in every unit of the five daily prayers, before carrying the first seventy four verses of Al-Baqara, the long Medinan sura that gives this whole juz its center of gravity. The hizb's early verses sort people into the mindful, the openly disbelieving and the hypocritical, then argue for God's oneness from the ordinary workings of the world, rain, crops, the turning of day into night. Adam's creation follows, with the angels commanded to bow before him and Iblis refusing, the same episode this atlas already records under the Fall.
The largest block of the hizb is an extended address to the Children of Israel, recalling the favor shown them out of Egypt and the failures that followed it: the golden calf made in Moses's absence, the demand to see God directly, manna and quails provided in the wilderness. It closes with the strange, much discussed instruction to slaughter a cow to settle a killing within the community, the episode that gives the whole sura its name even though it occupies only a handful of its two hundred and eighty six verses.
Hizb 1 ends partway through that account. The sura's address, increasingly turned toward the Israelites' descendants and then toward the Prophet's own contemporaries, continues in Hizb 2 rather than closing here, which is the ordinary condition of a length based division: it stops where the count runs out, not where an argument does.