Prophethood Explained

Allah selected His Prophets from the descendants of Adam, took covenants
from them to faithfully act according to His Revelations and to propagate His
Message...

Allah sent His Prophets continously one after the other so that they might
remind human beings of the duties, which nature had laid upon them as a part of
the plan of their existence and as the fulfilment of the made by their spirits
on the day of creation.

These Prophets were to draw the attention of humanity towards the inherent
covenant and the blessings and bounties bestowed upon them by Him, to convey His
message to them, to teach them, to wisely use the treasures hidden in their
minds and intellects...

Allah Almighty has never left His creation without guidence and education
through His Prophets, without a Divine Book, without conclusive and effective
proof and without a clear path to salvation.

Nahjul Balagha: Sermon 1: pg 146