Not many of us realise the subtle and hidden secrets that lie behind our movements in salah (prayer). Some of us may even rush through it without giving much thought to the hidden intricacies and the hidden beauty. How many people stand in salah but their mind does not stand focused? How many people bow down but their inner soul refuses to bow? How many people prostrate but their heart fails to do so? And how many people pray but a prayer has not been written for them?
The secret beauty behind rising up from Ruku’
Below are 2 passages from Ibn al-Qayyim’s book ‘Asrar al-Salat’.
“… Then it has been prescribed for the servant to extol and praise his Lord as he is rising up from ruku’ (i.e. after bowing in prayer)*, rising up and returning to his best pose**. So he exalts and praises his Lord as he returns to the best of forms because Allah has guided him to attain this humbleness which others have been prevented from attaining.
He is returned to a state of uprightness, standing up to be in his Lord’s service. He stands in front of Him just as he stood in front of Him during recitation (when reciting al-Fatiha), and for that reason it is prescribed that he praises and exalts Him just like he praised and exalted Him during the recitation.
And there is a special meaning to this rising; it is a state that reaches and penetrates the heart… It is for this reason that the Messenger of Allah (sallallahu `alayhi wa sallam) used to prolong this standing (after the ruku’) just as he prolonged the ruku‘ and sujud (prostration). He used to praise Allah much therein and exalt Him…
And when in the night prayer, he (sallallahu `alayhi wa sallam) used to repeatedly say during this standing after the ruku’, ‘For my Lord is all Praise, for my Lord is all Praise.’ 
Repetition within the Prayer
“… And it has been prescribed for the servant to repeat these actions and words (i.e. repeat recitation of al-Fatiha, ruku’, sujud etc, in the prayer) as it is a source of nourishment for the heart and soul. There is no strength in them (the heart and soul) except by this.
Repeating it is just like repeatedly eating food – mouthful after mouthful until a person eats his fill, and drinking again and again until his thirst is quenched. If a hungry person only took one mouthful of food and then pushed his food away, what will that mouthful do for him? In fact, it may even cause him to become hungrier!
For this reason, one of the Salaf said: ‘A person who prays but does not find tranquillity in his prayer is like a person who is hungry, then food is brought to him but he only takes one or two handfuls. What will it then do for him?’
 Reported by Abu Dawud and al-Nasa’i; declared sahih by al-Albani
* Rifa’a ibn Rafi’ said, “One day we were praying behind the Messenger of Allah (sallallahu `alayhi wa sallam) when the Messenger of Allah (sallallahu `alayhi wa sallam) raised his head from ruku’ and said, ‘Allah hears the one who praises Him’ (Sami’ Allahu liman hamidah). A man behind him said, ‘Our Lord, praise belongs to You – blessed, pure and abundant praise’ (Rabbana wa laka’l-hamd kathiran tayyiban mubarakan fihi). When the Messenger of Allah (sallallahu `alayhi wa sallam) had finished, he said, ‘Who was it who spoke just now?’ The man said, ‘I did, Messenger of Allah,’ and the Messenger of Allah (sallallahu `alayhi wa sallam) said, ‘I saw more than thirty angels rushing to see which one of them would record it first.’”
** By ‘best pose’ Ibn al-Qayyim is refering to the verse in Surah al-Tin: “… And We have indeed created Man in the best of forms.” [al-Tin: 4] – i.e. with an upright posture.