Nothing has been mentioned in the texts obligating the manner of which adhkaar must be done, whether silently or audibly. It is a broad matter which must be interpreted in its broadness. It is likewise not appropriate to restrict a general affair to a particular manner except in the existence of substantiating evidence.
There are some reports from the Prophet that evince the practice of invoking peace and blessings upon him audibly after the adhan.
Abu al-Dardau narrated that upon hearing the adhan, the Messenger of Allah would say, “O Allah! Lord of this comprehensive call and current prayer, grant Muhammad his request on the Day of Judgment.” Those around him would hear him making this supplication, and he liked them to supplicate with the same after the adhan. He said, “Whosoever supplicates with the same when he hears the Muadhin calling out the adhan, the intercession of Muhammad, peace and blessings be upon him and his family, becomes mandatory upon him on the Day of Judgment” [Reported by at-Tabari in his Al-Mu’jam Al-Kabeer).
The Divine injunctions in the Qur’an on making adhkaar in general and after prayers in particular are general. These verses include Q 33: 41-41, Q 18: 28, Q 4: 103… A general injunction (mutlaq) must be implemented as such until something comes to restrict it.
Some ahaadith indicate the permissibility of making adhkaar audibly after prayers. Imam Bukhari and Muslim reported that Ibn Abbas narrated that during the Prophet’s lifetime, voices would be raised in dhikr after the obligatory prayer. He said, “I would know that prayers had finished when I would hear dhikr being made.” In another wording of the hadith, he said, “I would know that the Prophet had finished praying when I would hear the takbir.”
The apparent meaning of the hadith maintains the permissibility of making Adhkar audibly after prayers as for the argument that the Prophet was teaching the congregants to make Dhikr lacks evidence.
Abu Hurayrah narrated that the Prophet said, “Allah the Almighty says, ‘I am as my servant expects me to be. I am with him when he makes mention of Me; if he makes mention of Me to himself, I make mention of him to Myself. If he makes mention of Me in an assembly, I make mention of him in a better assembly. If he draws near to me a hand span, I draw near to him an arm’s length and if he draws near to me an arm’s length, I draw near to him a fathom’s length. If he comes to me walking, I go to him at speed” (Bukhari and Muslim).
Ibn al-Jazariy wrote in his Miftaah al-Hisnu al-Hasiin, “This hadith indicates the permissibility of making dhikr audibly, contrary to the opinion of those who forbid it.”
Imam Suyuti wrote in his Natijatu al-Fikr fil Jahr bil Dhikr, “Mentioning someone in an assembly is always audible.”
Al-Suyuti mentioned in his treatise 25 ahaadith, all of which point to the permissibility of making dhikr audibly. After mentioning the ahadith, he said, “Upon contemplating the ahaadith, one will note there is no aversion whatsoever to audible dhikr; rather, they indicate its recommendation either explicitly or implicitly. Their inconsistency with the hadith stating that the best kind of dhikr is that which is made silently corresponds to the inconsistency between the ahadith on reading the Qur’an audibly and the ahaadith on reading it silently, in comparison to the hadith on giving alms in secret. In reconciling between the ahaadith, An-Nawawi mentions the virtues of both. He said that making dhikr silently is better for a person who fears hypocrisy or if his audible dhikr may harm others who are either praying or asleep. Otherwise, audible dhikr is better because it involves greater action, its benefit transcends to those who are listening, and it stirs the heart of the invoker and energizes his determination to contemplate. Moreover, it drives away sleep and increases energy. Some people have said that it is recommended to recite the Qur’an audibly at some times and silently at others. This is because a person who recites the Qur’an silently may become bored and so resorts to reciting it audibly while a person who recites the Qur’an audibly may become fatigued and so resorts to reciting it silently.’ The same is applied to dhikr and in this manner we reconcile between the inconsistent ahaadith.”
Making the voice be in an intermediate level during adhkaar is a recommended act. This is due to Allah’s words in Suratu Israa verse 110 “Say: And be not loud-voiced in your worship nor yet silent therein, but follow a way between”.
Anyone who argues that this verse is pertaining to the recitation of Qur’an only will be wrong. This verse revealed in Makkah, as a narration says the reason behind its revelation was the Mushrikoon who made jest of the Prophet while he recites loud. Then, the narrations of Abu Bishr Ja’far bn Iyaas and Dahaak from Ibn Abbas say when the Prophet migrated to Medina, the ruling of not making the recitation loud becomes null and abrogated.
However, the narration from Ikrimah, from Ibn Abbas says this verse was revealed on Dua (adhkaar) and not Qur’an. The same reported by Thawriy, Maalik, from Hisham bn Urwah, from his father, from Aaisha(radiya Allahu anhaa). And from Mujaahid, Sa’eed bn Jubayr, Makhuul, and Urwah bn Zubayr. Reported in Saheeh Bukhari, Saheeh Muslim.
And if we go by it being a revelation for the Qur’an (which was later abrogated in Medina), certainly the Qur’an is the fundamental source of Dua and Adhkaar.
Abu Qutadah narrated that the Prophet went out one night only to find Abu Bakr praying in a low voice. He then passed by Umar who was praying in a loud voice. When the two of them were present before the Prophet, he said, “I passed by you, Abu Bakr, when you were praying in a low voice.” Abu Bakr replied, “I made myself heard to the One upon Whom I called.” The Prophet said, “Raise your voice more.” Then he addressed Umar saying, “I passed by you and you were praying in a loud voice.” ‘Umar replied, “O Messenger of Allah! I rouse the drowsy and drive out the Devil.” The Prophet said, “Lower your voice some.”
Some of the Salaf were of the opinion that it is preferred to raise one’s voice when saying the adhkaar after the five daily prayers. They based this opinion on the hadith of Ibn Abbas quoted above, in which he said, “It was by hearing [the dhikr made after the prayer] that I knew they had finished.” This also involves more actions and its benefit is more conducive to (producing) contemplation and waking the hearts of those who are not heedful.
This differences whether to make Adhkar in a loud voice or silently depends on the person, the state (they are in), the time, and the purpose. Whenever one fears show-off or bringing harm to someone else [by raising one’s voice], lowering one’s voice is better, and whenever these conditions are absent, raising one’s voice is better.
Accordingly, raising one’s voice during Adhkar is not a reprehensible innovation (bid’ah), and there is nothing blameworthy about it. In fact, it could be more effective in involving the heart and bringing about concentration, as long as one is able to avoid show-off in his heart. To tag such bid’ah is extremism laced with ignorance.
Objection is not for issues over which there is a difference of opinion with convincing evidences. Whoever wishes may make his adhkar audibly and whoever wishes may make his silently.