Salah is Tranquillity for Worshippers and Allah's Gift to the Believers

It is imperative for you to know that salah is, without any doubt, the domain of tranquillity for devotees (muhibbin), the enjoyment of the souls of monotheists (muwahidin), the garden of the worshippers ('abidin), the essence of enjoyment of the humble ones (kashi'in), the test of the sincere ones (sadiqin), and the scale measuring the mettle of those embarking on the right path (salikin). It is truly a divine Mercy that Allah has gifted to His believing servants, that He has Guided them to, and acquainted them with. He delegated His truthful and honest Messenger, Prophet Muhammad, upon whom be peace, to deliver this gift to His believing servants in order that they may attain a noble status with Him. Through its means He dignifies, honours and showers them with His Mercy, and allows them to win His nearness. He bestows upon His believing servants all this although He is no need of them, He just wants to lavish them with this gracious gift to show His Favour upon them and bring their hearts and bodies altogether into His servitude.

He, the Most Exalted, endows the heart of the knower of Allah (i.e. the one who recognises the true status of Allah; acting upon this knowledge by living as His real slave) by enabling him to reap the best of its harvest; turning to Him, Exalted be He, rejoicing in His closeness, basking in His love, enjoying standing before Him [in salah], dismissing everything except Him [from his heart] as soon as he commences worship, and fulfilling the rights of his servitude to Him, inwardly and outwardly, in order for his worship to be in a manner that pleases Allah.

Even as Allah tested His servants by creating them with innate lusts and desires (shahwa) and exposing them to external temptations, His Mercy and Kindness mandated that Allah, the Most High, give His servants a feast (i.e. salah) comprising of several kinds of delicacies, nourishments, gifts and grants (to help them repel these desires and temptations). [As Ibn Mas'ud, may Allah be pleased with him, used to say:

"Indeed, this Qur'an is the banquet of Allah; so take from it as much as you can (i.e. learn from it) for I know nothing more unworthy than a house in which there is nothing of the Word of Allah. The heart which contains nothing of the Word of Allah goes to ruin like a house in which no-one lives."

And He did invite them to attend this banquet on a daily basis not once, but five times a day - and he distinguished each served course of his banquet (i.e. the actions of salah) with a unique flavour and a special benefit to perfect the pleasures and complement the benefits they attain and (help them to) perfect their 'ubudiyyah (servitude) to Allah. Thus, not only did He make every act of worship performed in salah a means of remedy to atone for the (minor) sins they committed, but rewarded them with a special light for praying. In fact, salah brings forth light and strength into the heart (qalb), increases the share of one's provisions in this life, inspires others to love (muhabba) the one who prays, and lets the Angels and also the earth with its mountains, trees and rivers rejoice. Furthermore, on the Day of Judgement, when the believing servants (of Allah) meet their Lord, their salah shall turn into light and transform into reward.

Before attending the feast their hearts endured starvation, thirst and nakedness but as soon as they commence the worship (i.e. salah), all that shall come to become the opposite, hence they shall leave the feat with stomachs full, throats moistened and bodies attired.

 Chapter 1.1 of The Inner Dimensions of the Prayer by Ibn Qayyim al-Jawziyyah, published by Dar as-Sunnah Publishers, Birmingham UK, 2013 with slight stylistic modifications to the text. The quote from Ibn Mas'ud, shown here in the main text for easier reading, is not in the text of Ibn Al-Qayyim but instead is a footnote to it added by the publishers.