Dhikr of Allah Ta'ala is the most excellent act of Allah's servants and is stressed over a hundred times in the Holy Qur'an. It is the most praiseworthy work to earn Allah's pleasure, the most effective weapon to overcome the enemy, and the most deserving of deeds in reward. It is the flag of Islam, the polish of hearts, the essence of the science of faith, the immunisation against hypocrisy, the head of worship, and the key of all success. There are no restrictions on the modality, frequency, or timing of dhikr whatsoever. The restrictions on modality pertain to certain specific obligatory acts which are not the issue here, such as Salat. The Shari`a (Islamic Law) is clear and everyone knows what they have to do. Indeed, the Prophet (sallallahu 'alahi wasallam) said that the People of Paradise will only regret one thing: not having made enough dhikr in the world! Are not those who are making up reasons to discourage others from making dhikr afraid of Allah Ta'ala in this tremendous matter?
What The Qur'an Says About Dhikr-Allah
"Those who remember Allah while standing , sitting, and lying on their sides" (3:191)
"Those men and women who engage much in Allah's praise. For them has Allah prepared forgiveness and a great reward." (33:35(Quran )
"He is successful who purifies himself, and remembers the name of his Lord, and so prays." (87:14-15)
Allah Ta'ala said in His Book: "And mention the name of your Lord and devote yourself to Him with a complete devotion" (73:8).
"Those who believe, and whose hearts find comfort in the remembrance of Allah! " Behold in the Remembrance of Allah do hearts find satisfaction." (13-28)
"O ye who believe let not your riches or your children divert you from the Remembrance of Allah if any act thus, the loss is their own." (63:9)
"Then do ye remember Me I will remember you." (2-152)
"Men whom neither traffic nor merchandise can divert from Remembrance of Allah nor from regular Salaat, nor from regular practice of Zakaat." (24-37)
"He who turns away from the remembrance of His Lord He will cause him to undergo a severe Penalty." (72-17)
What Ahadith Say About Dhikr-Allah
Hadith Qudsi, "Those that remember Me in their heart, I remember them in My heart; and those that remember Me in a gathering (i.e. that make mention of Me), I remember them (i.e. make mention of them) in a gathering better than theirs."
Dhikr in a gathering can only be done aloud and in unison. The above hadith thus constitutes proof that dhikr done outloud in a gathering is an exalted kind of dhikr which is mentioned at the Highest Assembly (al-mala' al-a`la.)
Hadhrat Jabir (Radi Allahu anhu) reported that the Prophet (Peace be upon him), said: "The best remembrance of Allah is to repeat la ilaha illallah and the best prayer (du'a) is al-hamdu lillah (all praise belongs to Allah)." (Narrated by Nasa'i, Ibn Majah, and Hakim who declared its chain sound)
In Bukhari and Muslim: The Prophet (Peace be upon him) said that Allah Ta'ala has angels roaming the roads to find the people of dhikr, i.e. those who say La Ilaha Illallah and similar expressions, and when they find a group of people (qawm) reciting dhikr, they call each other and encompass them in layers until the first heaven -- the location of which is in Allah's knowledge. (This is to say, an unlimited number of angels are going to be over that group).
This is further indicated by the hadith Qudsi which runs: "Allah says: I am to my servant as he expects of Me, I am with him when he remembers Me. If he remembers Me in his heart, I remember him to Myself, and if he remembers me in an assembly, I mention him in an assembly better than his..." (Bukhari and Muslim)
Thus, silent dhikr is differentiated from dhikr said outloud by His saying: "Remembers Me within himself," meaning: "silently," and "in an assembly," meaning "aloud."
The Holy Prophet (Peace be upon him) said: hatta yaqulu majnun "Remember Allah Ta'ala as much as you want, until people say that you are crazy and foolish"
(Narrated by Ahmad in his Musnad, Ibn Hibban in his Sahih, and al-Hakim who declared it sahih); that is: do not care about them!
Ibn `Umar (Radi Allahu Anhu) reported that the Prophet (Peace be upon him) said: "When you pass by the gardens of Paradise, avail yourselves of them." The Companions asked: "What are the gardens of Paradise, O Messenger of Allah?" He replied: "The circles of dhikr. There are roaming angels of Allah who go about looking for the circles of dhikr, and when they find them they surround them closely."
(This include Quran and Durud Shareef Khatam). Tirmidhi narrated it (hasan gharib) and Ahmad.
Abu Sa`id Al-Khudri and Abu Huraira (Radi Allahu anhum ajma'een)reported that the Prophet (Peace be upon him) said, "When any group of men remember Allah, angels surround them and mercy covers them, tranquility descends upon them, and Allah mentions them to those who are with Him." Narrated by Muslim, Tirmidhi, Ahmad, Ibn Majah, and Bayhaqi.
Muslim, Ahmad, and Tirmidhi narrate from Mu`awiya (Radi Allahu anhu) that the Prophet (Peace be upon him) went out to a circle of his Companions and asked: "What made you sit here?" They said: "We are sitting here in order to remember Allah (nadhkurullaha) and to glorify Him (wa nahmaduhu) because He guided us to the path of Islam and he conferred favours upon us." Thereupon he adjured them by Allah and asked if that was the only purpose of their sitting there. They said: "By Allah, we are sitting here for this purpose only." At this the Prophet (Peace be upon him) said: "I am not asking you to take an oath because of any misapprehension against you, but only because Jibraeel ('alahis salam) came to me and informed me that Allah, the Exalted and Glorious, was telling the angels that He is proud of you!" Note that the hadith stated jalasna -- we sat -- in the plural, not singular. It referred to an association of people in a group, not one person.
The Prophet, peace be upon him, would often tell his Companions, "Shall I tell you about the best of deeds, the most pure in the sight of your Lord, about the one that is of the highest order and is far better for you than spending gold and silver, even better for you than meeting your enemies in the battlefield where you strike at their necks and they at yours?" The Companions replied, "Yes, O Messenger of Allah!" The Prophet, peace be upon him, said, "Remembrance of Allah." (Narrated by Tirmidhi, Ahmad, and Hakim who declared its chain of narrators sound)
The Prophet (Peace be upon him) said: "He who loves something mentions it much".
Qadi Thana'ullah Panipati said in his Tafsir Mazhari (10:111): "Know that this verse points to the repetition of the name of the Essence (ism al-dhat)," that is: "Allah." The same meaning is intimated also by the end of verse 6:91 in Surat al-An`am: "Say ALLAH. Then leave them to their play and vain wrangling."