Shaykh Abdul-Muhsin Al-Abbaad was asked:

Question:

“How can Adam be a Prophet when there was no books before him?”

Answer:

“It is well-known that it was revealed to him with what to worship Allah, Exalted with and likewise his sons. So he was a Messenger to his children. They did not know what to worship Allah with except through his path” End translation. [Sharh Arba’een an-Nawawiyyah no. 4]

Translated by

Faisal Ibn Abdul Qaadir Ibn Hassan
Abu Sulaymaan