Four Principles of Worship
“(The Âyah): “You alone do we worship.” [Sûrah al-Fâtihah 1:5] is built upon four principles:- Ascertaining what Allâh and His Messenger love and are pleased with, from [i] the sayings of the heart and [ii] of the tongue; and [iii] the actions of the heart and [iv] of the limbs.
So al-’ubûdiyyah (servitude and slavery to Allâh) is a comprehensive term for all these for stages. The one who actualizes them has indeed actualized: “You alone do we worship.”
The saying of the heart: It is i’tiqâd (belief) in what Allâh - the Most Perfect - informed about His Self; concerning His Names, His Attributes, His Actions, His Angels, and all that He sent upon the tongue of His Messenger sallallâhu ’alayhi wa sallam.
The saying of the tongue: It is to inform and convey (what Allâh has revealed), to call to it, defend it, to explain the false innovations which oppose it, to establish its remembrance and to convey what it orders.
The action of the heart: Such as love for Him, reliance upon Him, repenting to Him, having fear and hope in Him, making the Dîn purely and sincerely for Him, having patience in what He orders and prohibits, having patience with what He decrees and being pleased with it, having allegiance and enmity for His sake, humbling oneself in front of Him and having humility in front of Him, becoming tranquil with Him and other than this from the actions of the heart which are actually connected to the action of the limbs ... and actions of the limbs without the action of the heart is of little benefit, if any benefit at all.
The action of the limbs: Such as Prayer and Jihâd, attending the Jumu’ah and being with the Jamâ’ah, aiding those who are unable and displaying goodness and kindness to the creation, and other than this.”
[Madârijus-Sâlikîn (1/100-101)]
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Reference:
Fawaa'id - Points of Benefit - by Imâm Ibn Qayyim al-Jawziyyah