The truth of the matter is that the prayer was established by the Blessed Messenger (saw). It is a mass transmitted sunnah. The hadith are written records for those who need to furnish proofs for things that were found to be objectionable. Things that stood out as different needed to have a proof or evidence, more so than a mass practiced sunnah, where the people picked up from those who preceded them and from those who preceded them. People were generally in the habit of asking for chains of narration / testimonies of proof for practices that were out of the ordinary. Ibn Sīrīn (d. 110 AH) explains, “In the early period, no one would ask about isnād. But when the strife occurred people would say, “Name for us your sources.” Source: (Muslim, Introduction to his Sahīh, p.11.)
An excellent example of this is in the Sunan of Abu Dawud. He has reported three hadith about where to place the hands in the prayer. This shows his awareness of the hadith. This does not indicate that he did all three. One would be hard pressed to provide evidence that Abu Dawud himself did all three acts in the prayer.
– Keeping the hands on chest
It was reported from Sulaiman bin Musa, from Tawus who said: Allah’s Messenger (PBUH) used to place his right hand on his left hand, then grasp both of them on his chest while he was praying.
(Hadith No. 759, Book of Salat, Sunan Abu Dawud, Vol. 1).
– Keeping the hands on abdomen above the navel
Jarir Ad-Dabbi narrated: I saw Ali praying while grasping his left hand with his right hand, over the wrist joint, above the navel.
(Hadith No. 757, Book of Salat, Sunan Abu Dawud, Vol. 1).
– Keeping the hands below the navel
Narrated Ali ibn AbuTalib:
AbuJuhayfah said: Ali said that it is a sunnah to place one hand on the other in prayer below the navel. (Hadith No. 756, Book of Salah, Sunan Abu Dawud, Vol. 1)
It is not reasonable to assume that Abu Dawud did all three acts in the prayer. Rather, it is sensible that he reported such hadith to show that he has an awareness concerning them.