Salah is the most important forms of all worship. In fact, it is the first and foremost item to be reckoned for on the Day of Qiyaamah.Nabi SAW is reported to have said: "Salah is the only way of differentiation between Kufr and Islam." There are many Ahaadith about Salah, which I have collected in a separate book. Blessings of Nafl (non-obligatory) Salah Nabi SAW reported that Allah told him: "My anger descends upon a person who bears ill-will towards My friends, and only those are blessed with My love who punctually carry out Fardh (obligatory) injunctions. 

A person keeps on advancing in my esteem through nafl, till I choose him as 'My beloved'. I then become his ear by which he listens, his eye by which he looks, his hands by which he holds, and his feet by which he walks (i.e. his listening, looking, holding and walking are according to My wishes and commands, and he would never even dream of using any part of his body in any action against My commands). If such a person asks for anything, I grant it to him and if he seeks My protection, I do protect him."

Those people are really blessed who, after performing their Fardh, are in the habit of observing Nafl abundantly. MayAllahgive me and all my friends the strength to earn this blessing. Nabi SAW spends the whole night in Salaah A certain person asked A'ishah: "Tell me something noteworthy concerning Nabi SAW." She answered: "There was nothing which was not unusual about him. Everything he did was noteworthy. One night he came and lay down beside me. After sometime, he got up saying,
 'Now let me pray to my Lord, the Sustainer'."

With this, he stood up in Salah, humbling himself before his Creator with such sincerity that tears rolled down his cheeks to his beard and on to his chest. He then bowed for Ruku' and Sajdah, and his tears flowed down as fast as before and after raising his head from his Sajdah, he continued weeping in this manner till Hadhrat Bilalannounced the approach of Fajr Salah. I pleaded with him: "O, Nabi of Allah! you are sinless, as Allah has in His kindness, forgiven your each and every sin (even if committed) in the past and which may happen in the life to come (XLVIII: 2) and still you grieve so much."

Nabi SAW replied: 

"Why should I then not be a grateful slave of Allah ?" He then added,

 "Why should I not be praying like this when Allah has today revealed to me these verses?"­

Verily in the creation of the Heavens and the Earth, and in the alternating of night and day, are signs (of His Sovereignty) for men of understanding. They who remember Allah, standing, sitting and reclining . . . (S3:V190-191)

It has been reported in many Ahaadith that Nabi's SAW feet would get swollen because of his very long ra-kaats in Salaah. People tried to reason with him: "O, Nabi of Allah! You are sinless and you still labour so hard!" He would reply: "Should I not be a grateful slave of my Allah, then ?"