A worshipper is required to show humility (khushoo) in his prayer and have complete focus of mind and presence of heart.
Allah, may He be exalted, says (interpretation of the meaning):
“Certainly will the believers have succeeded:
They who are during their prayer humbly submissive [khaashi‘oon]”
Focusing on prayer and being humble in it are among the most important issues and therefore the essence of the prayer. Therefore we must pay attention to focusing with proper humility in the prayer and performing it in a tranquil and unhurried manner, when prostrating and bowing, between the two prostrations, and after bowing when standing up again; it should be done in a tranquil and unhurried manner.
If the worshipper fails to focus his mind and show humility in prayer and he does his prayer in a hurried manner and with no concentration then his prayer becomes invalid.
But if a believer is at ease and performs his prayer in an unhurried manner and if sometimes his mind wander and he forgets something then his prayer does not become invalid, but he will not have any reward for his prayer except inasmuch as his mind was focused and he showed proper humility and mindfulness of Allah; he will have the reward for that, but as for the parts in which he was not focused, he will miss out on the reward thereof.
Therefore he must focus more on his prayer and do it in calm and without any haste, showing humility to Allah, may He be glorified and exalted, so that he will have the reward thereof in full.
Each and every action in prayer must be done with ease and calmness. He should elongate his prostrations a bit so that he will have enough time to focus. What he should do is move with ease, so that he adopts the right posture with every vertebra in place and so that he will have enough time to say Subhaana Rabbiy al-‘Azeem (Glory be to my Lord the Almighty) when bowing and to say Rabbana wa laka’l-hamd(my Lord and to You be praise) when standing up straight after bowing, and to say Subhaana Rabbiy al-A‘la (Glory be to my Lord Most High) when prostrating, and to say Rabb ighfir (Lord forgive me) between the two prostrations.
When the Prophet (blessings and peace of Allah be upon him) saw a man who did not pray in a calm and unhurried manner – rather he pecked his way through the prayer – he instructed that man to repeat his prayer, and said: “Pray, for you have not prayed.”
Praying in an unhurried manner is one of the most important aspects of khushoo and this is something that is required in prayer, when bowing and prostrating, between the two prostrations, and when standing up straight after bowing. This is called tama’neena, which means being calm and at ease, proceeding in an unhurried manner. It is also called khushoo‘, which means having proper focus and humility when praying.
And Allah knows best.