The Kinds of Worship

Imam Sadiq (as) says: 
العُبَّادُ ثَلاَثَةٌ: قَوْمٌ عَبَدُوا اللَهَ خَوْفاً فَتِلْكَ عِبَادَةُ العَبِيدِ. وَقَوْمٌ عَبَدُوا اللَهَ طَمَعاً فَتِلْكَ عِبَادَةُ الاُجَرَاءِ. وَقَوْمٌ عَبَدُوا اللَهَ حُبّاً فَتِلْكَ عِبَادَةُ الاَحْرَارِ
The servants are of three kinds: a group worship God for fear, and that is the worship of slaves; another group worship God for the sake of greed, and that is the worship of merchants; yet there is another group that worships God for the sake of His love, and that is the worship of freemen. 

Careful reflection over these words will show that the worship of the first two groups is not real worship, because their worship is not of God and for the sake of God but derives from their egoism and self‑worship. In reality they have worshipped themselves, not God, the Exalted, for the motives behind their worship are their self‑seeking appetites and attachments. And since self‑worship is not consistent with the worship of God, therefore, at first sight, this group are unbelievers in God and His Divinity. However, as the Noble Qur'an explicitly describes God‑worship as being innate to the human being, it has negated any kind of change and alteration in creation:

فَأَقِمْ وَجْهَكَ لِلدِّينِ حَنِيفًا فِطْرَةَ اللَّهِ الَّتِي فَطَرَ النَّاسَ عَلَيْهَا لَا تَبْدِيلَ لِخَلْقِ اللَّهِ ذَلِكَ الدِّينُ الْقَيِّمُ وَلَكِنَّ أَكْثَرَ النَّاسِ لَا يَعْلَمُونَ

 [So set your face toward religion as a man of pure faith (hand; that is theoriginal creation of God wherewith He originated mankind. There is nochanging the creation of God. That is the right religion, but most people donot know it.] (30:30)

Accordingly, this is not a deviation of man from the path of God‑worship but from the path of tawhid, as they do not consider God to be One in His Act and Attribute and so make others His partners. Accordingly, the Qur'an, throughout, has stood up to affirm the Unity of God and to negate any partner in relation to Him. On this basis, the first two groups consider God as a sharer in their purpose, and while they worship God they do not leave off worshiping themselves, and carry out their acts of worship with a dual purpose and this is shirk (polytheism). In reality these two groups are mushrik (polytheist) in respect of God, the Exalted, which is unforgivable in accordance With express Qur'anic texts:

إِنَّ اللّهَ لاَ يَغْفِرُ أَن يُشْرَكَ بِهِ وَيَغْفِرُ مَا دُونَ ذَلِكَ لِمَن يَشَاء وَمَن يُشْرِكْ بِاللّهِ فَقَدِ افْتَرَى إِثْمًا عَظِيمًا

[Verily, God does not forgive that anyone should assign partners to Him, yet He forgives anything besides that for anyone He wills.] (4:48)

Accordingly, their worship will never be fruitful or bring them close to God, the Exalted.

As to the third group of persons, who worship God for their love of Him, that is the worship of freemen, and it is mentioned in some traditions

that:

تِلْكَ عِبَادَةُ الكِرَام

[That is the worship of the noble ones.]

This is the real and correct kind of worship which is not attained by anyone except the pure ones of the Divine Threshold:

فَهَذَا مَقَامٌ مَكْنُونٌ لاَ يَمَسُّهُ إلاَّ الْمُطَهَّرُون.

[This is the hidden station, untouched by anyone except the pure ones.]

Love consists of attraction, that is one's being gravitated towards some thing or towards some reality. The third group consists of those who have based their worship on the foundation of love and attraction towards God, and they have no purpose in. view except being drawn towards Him and coming closer to Him. It is the sole attraction towards the Beloved that they feel in themselves which is the motive that drives them towards the Beloved and impels their journey towards His sanctity.

It is mentioned in some traditions that we should worship God, the Exalted, because He is worthy of worship. Obviously, this worthiness does not derive from the Divine Attributes but from the station of His Sacred Being, glorious is His Majesty and great is His station. Accordingly, it means that we must worship God because He is God.

إلَهِي مَا عَبَدْتُكَ خَوْفاً مِنْ نَارِكَ وَلاَ طَمَعاً فِي‌ جَنَّتِكَ، بَلْ   وَجَدْتُكَ أَهْلاً  لِلْعِبَادَةِ فَعَبَدْتك.             

[My God, I did not worship You for the fear of Your hell, nor in the hope of Your paradise. Rather, I found You worthy of worship and so I worshipped You.]

Source: Lubb al Lubab