Ishaq was the prophet and father of Prophet Ya'qub (Jacob). In Islamic tradition, Ishaq was the son of Prophet Ibrahim (Abraham) and Sarah, while Ya'qub was his prophetic son and successor in the family’s legacy of monotheistic teaching.
The Qur’an presents the birth of Ishaq as glad tidings given to Ibrahim and Sarah despite their advanced age. It also mentions that the couple would receive news of Ya'qub after Ishaq, making Ya'qub the next generation in this prophetic lineage. Ya'qub is also known as Isra'il.
A common mix-up is confusing Ishaq with Isma'il. Both were sons of Ibrahim and prophets, but Isma'il was Ishaq’s older half-brother and was the father of a different line. Yusuf (Joseph) was not Ya'qub’s father; he was one of Ya'qub’s sons. Ibrahim was Ya'qub’s grandfather, not his father. The Qur’an frequently mentions Ishaq alongside Ibrahim and Ya'qub, reinforcing the family relationship.