You should know - may Allah have mercy upon you - that when the slave [of Allah] leaves his house to go to the mosque, that he is going to face Allah, the Irresistible, the One, the Omnipotent, the Exalted in Might, the Oft-forgiving, in the knowledge that nothing is hidden from Allah, wherever it might be, and that nothing is hidden from Allah and that even something as small as a mustard seed is not concealed from Him, nor even something smaller, nor larger - in the seven earths or the seven heavens, in the seven seas or the lofty mountains, fixed and firm. And verily, the mosque to which he comes is one of the Houses of Allah. He desires only Allah and he sets out to one of Allah's Houses, which:
"Allah has permitted to be raised to honour, for the celebration in them of His Name: In them He is glorified in the mornings and the evenings [over and over] by men whom neither traffic nor merchandise can divert from the practice of regular charity: Their [only] fear is for the Day when hearts and eyes will be transformed." [Al-Qur'an 24:36-37]
So when anyone from amongst you sets out from his house (for the mosque) he should say quietly to himself words of remembrance [of Allah] - words unconnected with the affairs and business of this world. He should set out calmly, somberly, for this is what the Prophet, sallallahu 'alayhi wa sallam, ordered us to do; he should set out with (his heart full of) longing and desire [for Allah's pleasure] and fear and apprehension [of Allah's anger] and with humility and meekness towards Allah. For the more humble, the more meek, the more submissive he is to Allah, the more virtuous and righteous does he become in salah and the greater becomes his reward, and the more noble and nearer to Allah becomes the worshipper. But should he be filled with pride, Allah will destroy him and will reject his deeds, for the deeds of the proud are never accepted. It has been narrated in a hadith concerning Prophet Ibrahim, 'alayhis salam, Allah's Khalil, that he spent the night in worship and remembrance of Allah, and in the morning, he was pleased with the night's worship and he said: "How Good is the Rabb (Lord), and how good is the slave, Ibrahim ('alayhis salam)." On the following day, finding none to share his food with him - and he loved to share his food - he took his food outside to the road and sat, waiting for any passerby to eat with him. Then two angels descended from the heavens and approached him.
So he invited them to eat with him and they accepted. Then Ibrahim 'alayhis salam suggested that they approach a nearby garden which contained a fresh water spring. They agreed to this and approached the garden, only to find that the spring had run underground, so there was no water. This was a severe blow to Ibrahim, 'alayhis salam, and he was embarrassed by what he had said (because there was no spring in evidence) and so the angels said to him: "Ask your Rabb to return the spring." He did so, but the spring did not appear, and this was a great blow to him and so he said to the angels: "You ask Allah." So one of them asked Him, and behold, the water returned, then the other supplicated Allah and the water flowed near to them. Then they informed him that his being impressed by his own standing in prayer the previous night had caused his supplication to be rejected. So beware - may Allah have mercy on you - of pride, for no deed will be accepted if it is accompanied by pride. Be humble in your salah. Should any of you stand in salah before his Rabb, he should know Allah, in his heart by the great blessings which He bestows upon him and the abundant favour which He grants him, for Allah has honoured him with great goodness, but he has saddled himself with sins. Therefore it is incumbent upon him to be excessive in his humility and meekness towards Allah.
It is reported from Abud-Darda that he said, "That may face be covered in dust for my Rabb (is most loved by me) - for that is the best kind of worship for Allah." So let none of you fear the dust, nor find it distasteful to make sujud in it, for there is no doubt that every one of you comes from it (i.e. mankind was created from dust). Nor should any of you fear an excess of it, for verily, it is by this means that one attempts to attain freedom from slavery and salvation from the Hellfire - a fire before which the fixed lofty mountains which were placed as pegs (holding the earth) could not stand, nor the seven strong heavens, built one above another, which are placed as a well graded canopy over us, nor the earth, which was placed as a dwelling for us, nor the seven seas, of which none knows their depths or their size except the One Who created them. Then what about us, with our feeble bodies, our delicate bones, our flimsy skin? We seek refuge with Allah from the Fire!
So should any of you stand in salah - may Allah have mercy on you - then let him be as if he sees Allah before him, for though he may not see Allah, verily, Allah sees him. It is narrated in a hadith that Allah's Messenger, sallallahu 'alayhi wa sallam, advised a man, saying:
"Fear Allah as though you see Him, for verily, though you may not see Him, He sees you." [Something similar to this wording is quoted in the hadith in which the Prophet, sallallahu 'alayhi wa sallam spoke to Jibril, 'alayhis salam, informing him about the meaning of ihsan, as reported by Bukhari and Muslim]
This then, is the advice of the Prophet, sallallahu 'alayhi wa sallam, to the slave in all his affairs, so what about when he performs salah, when he stands before Allah, in a particular place, a sacred place, desiring Allah and turning his face towards Him? Does not his standing, his situation in salah merit the same ihsan as all his affairs? It says in a hadith:
"Verily, the slave, when he starts his salah, should turn his face to Allah, and he should not turn it away from Him until he leaves or turns to right and left." (That is, when he makes taslim at the end of the prayer) [Narrated by Ahmad, Abu Dawud and an-Nasa'i]
It is also narrated in a hadith:
"Verily, the slave, as long as he is in salah, possesses three qualities: Blessings are showered upon his head from the heavens above, the angels sit around him, from his feet to the heavens and a caller says: 'If the slave knew the One Who hears his whispered utterances, he would never leave his salah.' " [This narration was mentioned by Muhammad ibn Nasr al-Mirwazi in Kitab as-Salah from the hadith of al-Hasan al-Basri in a mursal form (an incomplete chain of narrations, in which no Companion is mentioned)]
Allah showers His Mercy upon the worshipper who approaches prayer in a state of humility and meekness towards Allah, in fear and supplicating Him with desire (for His Pleasure), and in hope (of His Mercy), making salah to his Rabb, his most important consideration, dedicating his whispered utterances to Him and his standing erect in worship and his ruku' and his sujud, poring out his heart and his feelings and struggling to perfect his acts of worship, for he knows not whether he will perform another prayer after it, or whether he will be overtaken (by death) before he can perform salah again. He stands before his Rabb, earnestly, with deep feelings, hoping for its acceptance and fearing its rejection, for verily, its acceptance is a cause for joy, while its rejection is a cause for misery and wretchedness. Nothing could be more important to you - O my brother - in this salah, or indeed in any of your actions [i.e. that Allah should accept them]. What is more deserving of your distress and misery, your fear - indeed your terror - you know not whether your salah will find favour with Allah at all, nor whether any of your good deeds will be accepted.
Do you know if your sins will be forgiven at all? After all this, you have no assurance that you will be spared from it (i.e. the punishment of the Hellfire). So who is more deserving of your tears and sadness [than Allah] - that He may accept from you (your deeds)? In addition to this, you know not whether or not you will awaken in the morning, nor if you will still be here in the evening - will you be given the good news of Paradise, or the bad news of the Hellfire? I only desire to warn you - O my brother - of this terrible danger. It is not fitting that you should be happy because of your family, your wealth or your children. It is a most amazing thing that you should continue to be unmindful, chasing after vain desires, wasting your time in disregard of this most important matter, for you are being driven at a fierce pace (towards death) day and night, hour by hour, like the blink of an eye. You should expect - O my brother - that your time may come at any moment and do not be unmindful of this great danger which may visit you. Most assuredly, you must (eventually) taste death.
Your time may come in the morning or in the evening. You will be separated from all that you possessed - either (to be rewarded with) Paradise or (to be punished in) the Hellfire. Descriptions and stories of them (have become) superfluous. Have you not heard - O my brother the words of the pious slave: "I am amazed concerning the Hellfire - how does the one who could flee from it sleep? And I am amazed concerning the Jannah - how does the one who desires it sleep? For by Allah! If you neither desire Paradise, nor fear the Hellfire, then you are destroyed and grievous will be your sorrow, interminable your sadness and without limit your tears; you will be amongst the wretched, the punished ones. So if you claim that you are amongst those who seek refuge from the Fire and desire Paradise, then strive for that which you seek and do not be misled by your worldly desires."