Narrated Mujahid:
That he asked Ibn ‘Abbas, “Is there a prostration Surat-al-Sad?” (38.24) Ibn Abbas said, “Yes,” and then recited: “We gave…So follow their guidance.” (6.85,90) Then he said, “He (David ) is one them (i.e. those prophets).” Mujahid narrated: I asked Ibn ‘Abbas (regarding the above Verse). He said, “Your Prophet (Muhammad) was one of those who were ordered to follow them.”
Sahih Bukhari, Volume 6, Book60, Number 156