Al-'Awwam bin Hawshab said:

I asked Mujahid about the prostration in (Soorat) Sad and he said: Yes, I asked Ibn ‘Abbas (رضي الله عنه) about it and he said: Have you read this verse: "and among his progeny Dawood (David), Sulaiman (Solomon)" (al-An'am 6:84) and at the end of it, it says: "So follow their guidance” (al-An'am 6:90). Your Prophet (ﷺ) was commanded to follow the example of Dawood.