Assalaamu `alaykum
As brother Dawaah mentioned... this is an issue over which scholars have differed.
The english .pdf is an abridgment of the book and not the full english book. If you check the link I gave you- you can find it there (i.e the arabic book)... where Shaykh al Albaanee mentions about it in more detail.
(83) Then he should stand straight up and remain still, such that
every bone returns to its place. This is a pillar.
When shaykh al- Albaanee explains the above hadeeth- he brings another hadeeth to explain it. He brings the narration of Abu Humayd al-Saa`idee in Bukhaari in which it describes the prayer of the Messenger of Allaah :saw2: and it mentions "حتى يعود كل فقار مكانه" [Untill all Faqaar returned to it's place.]
Some scholars mentioned that فقار refers to every bone- thus the hands should go back to where it was before rukoo`. Shaykh al- Albaanee refuted this mentioning that فقار means "عظام الصلب" (Literally- Bones of the backbone). This is what was generally understood by classical scholars. As we see, when Ibn Hajar explains this hadeeth in Fath al-Baari he mentions that فقار refers to عِظام الظَّهر (Bones of the back). So from that hadeeth we clearly understand that one stands up from Rukoo` untill all the bones in his back return to its place (i.e the person stands up and his back should be straight after rukoo`).
Having mentioned that... scholars like Ibn `Uthaymeen, Ibn Baaz and others mentioned the hadeeth of Sahl ibn Sa`d in Bukhaari- where he mentioned that the people were commanded to place the right hand over the left hand IN SALAAH.
So, Shaykh ibn `Uthaymeen argued that it does not mention 'In Qiyaam' rather it mentions in Salaah- so it is general and thus the right hand is to be placed over the left hand after rukoo`.
Al- Albaanee argued that this was not from the `amal of the salaf as no one mentioned the placing of the right hand over the left hand after Rukoo` and you have people on the other side argue back using the same point that the salaf did not mention about putting the hands to the sides after rukoo`. They also argued saying that Imaam Ahmad from the salaf talked about this and he mentioned that the Musalli has a choice (between putting the hands to the sides or placing the right hand over the left hand).
Many of the hanaabilah mentioned that the action of Imaam Ahmad was to put the hands to the sides and reported this from the Imaam, whereas the other hanaabilah argued that just because Imaam Ahmad did this- does not negate his statement... as speech is given precedence over action.
Whatever the case- the matter is flexible... as expressed by Imaam Ahmad. I personally stick to putting the right hand over the left hand after rukoo`.
Allaah knows best
Wassalaamu `alaykum
