Pillars of worship
Worship is based on three pillars:
Some scholars have maintained that they are four:
-Veneration [of Allah Almighty].
Actually, there is no contradiction between the previous two opinions. This is because hope springs from love since a person has no hope except in those he loves. Likewise, fear springs from veneration since a person fears none except a great thing.
Allah Almighty praised the Prophets and Messengers who worshiped Him through fear and hope. He says in the Qur'an:
Indeed, they used to hasten to good deeds and supplicate Us in hope and fear, and they were to Us humbly submissive. [Al-'Anbiya':90]
Likewise, Allah praised His believing servants who maintain hope and fear in His words:
Is one who is devoutly obedient during periods of the night, prostrating and standing [in prayer], fearing the Hereafter and hoping for the mercy of his Lord. [Az-Zumar:9]
and they hope for His mercy and fear His punishment. [Al-Isra':57]
They arise from [their] beds; they supplicate their Lord in fear and aspiration, and from what We have provided them, they spend. [As-Sajda:16]
And invoke Him in fear and aspiration. [Al-'Araf:56]
The above verses illustrate how the Prophets, Messengers and believing servants of Allah worship Him. So, whoever is better than them and perfect in his worship? Is the supplication of anyone other than them accepted? Of course no. This is because fear and hope are connected. Both of them are the key to Paradise and salvation from Hell fire.
If we to ask a believer the reason why he refrains from committing adultery [zina] although he is able to do it, he will immediately answer: "I fear Allah and hope for His reward." If we to ask a believer the reason why he observes the five obligatory prayers, he will immediately answer: "I fear Allah and hope for His reward."
A believer may love anything other than Allah; however, he does not fear it and vice versa. However, fear and hope must be together when it comes to Allah the Exalted. We have to love and fear Allah at the same time. Thus, a believer must bring together love, fear, hope and veneration.
It is not enough to worship Allah through love alone:
Worshipping Allah through love alone is not enough and erroneous. This is because it is void of venerating and fearing Allah Almighty. A believer who depends on love only in worshipping Allah does not refrain from committing prohibited actions; rather, he does not give heed to Allah's commands claiming that a lover does not torture his beloved. The Jews and Christians said the same in the Qur'an: "But the Jews and the Christians say, "We are the children of Allah and His beloved." [Al-Ma'ida:18]
The excessive Sufis says: "We worship Allah but not out of fearing His punishment or hoping for His reward; rather, we worship Him out of love."
Undoubtedly, this is an erroneous path and corrupted method that have evil consequences. This include, feeling secure from the plan of Allah which leads to leaving the religion. A person who excessively indulges in sins while seeking the mercy of Allah without repentance falls into illusion, arrogance and fake hope.
Likewise, depending on fear only in worshipping Allah without having love or hope is erroneous. Rather, it is invalid and corrupted. This is typically the methodology followed by the Kharijites who do not maintain love in their worship to Allah and thus they do not find pleasure or desire in worshipping Allah. Therefore, they see the Creator as a tyrant ruler or oppressor which consequently brings about despair and losing faith in Allah's mercy. This ultimately leads to disbelief and thinking bad in Allah. Allah Almighty says in the Qudsi hadith: "I am as My servant thinks of Me and I am with him wherever He remembers Me."
Jabir (may Allah be pleased with him) narrated that he heard the Messenger of Allah (peace and blessings be upon him) saying three days before his death: "No one of you should die unless he thinks well of Allah Almighty."
Thinking well of Allah is the catalyst for working hard which necessitates answering one's supplication, accepting repentance, forgiveness of sins and reward for doing good deeds. However, insisting on committing sins while thinking well of Allah that He will forgive, answer the supplication and give reward is nothing but ignorance, arrogance and foolishness.
A believing worshipper must love Allah other than anything else; he must venerate Allah other than anything else. Hope necessitates fearing Allah or it becomes secure; fear necessitates hope or it may become despair. Whenever a person fear another, he runs away form him; but when we fear Allah, we seek refuge in Him as per His words: "So flee to Allah." [Adh-Dhariyat: 50]
There is a well known statement of the righteous predecessors [Salaf]: "Whoever worships Allah through love only, he is infidel; whoever worships Allah through fear alone, he is a Hirarri; whoever worships Allah through hope alone, he is Murji'; and whoever worships Allah through fear, hope and love is a true believer."
 Recorded by al-Bukhari in al-Fath (7405) and Muslim (2675).
 Recorded by Muslim (2877)
See al-'Ubudiya p.128.