Seth (Shith) was born to Adam and Eve, after Cain killed Abel. God gave the Revelation to Seth after the death of Adam. God revealed 50 booklets to Seth, as narrated by Ibn Hibban that Abu Dharr al-Ghifariyy heard this from Prophet Muhammad. Seth conveyed the message of Islam to the people, telling the people the correct belief in God and the way to perform acceptable worship. All the humans were Muslim at that time, but still God gave the Revelation to Seth, and he taught and reminded the people.
Seth received a new ruling from God, different from the time of Prophet Adam. This ruling was that it is forbidden for the brother to marry his sister, whether she is his twin sister, or his sister who is not his twin.
Prophet Adam was ill for eleven days before he died. Prophet Adam passed a will to his son Seth, ordering him to keep it sealed from Cain and Cain’s son, due to their envy. Prophet Seth lived in Makkah and performed Hajj and ^Umrah (a pilgrimage with some similarity to Hajj) and stayed there until he died. Seth passed on the will to his child, Anush, and Anush passed the will to his son, Qaynan. Qaynan passed it to his son Mahlayil, and then to his son Yard, and then to his son Akhanukh, also known as Enoch (Idris).