Dhikr (Arabic: ذِكْر; Arabic pronunciation: [ðikr]; lit. 'remembrance, reminder, mention') is a form of Islamic worship in which phrases or prayers are repeatedly recited for the purpose of remembering God. It plays a central role in Sufism, and each Sufi order typically adopts a specific dhikr, accompanied by specific posture, breathing, and movement. In Sufism, dhikr refers to both the act of this remembrance as well as the prayers used in these acts of remembrance. Dhikr usually includes the names of God or supplication from the Quran or hadith. It may be counted with either one's fingers or prayer beads, and may be performed alone or with a collective group. A person who recites dhikr is called a dhākir (ذَاكِر; [ðaːkɪr]; lit. 'rememberer').

The Quran frequently refers to itself and other scriptures and prophetic messages as "reminders" (dhikrah, tadhkīrah), which is understood as a call to "remember" (dhikr) an innate knowledge of God humans already possess. The Quran uses the term dhikr to denote the reminder from God conveyed through the prophets and messengers, as well as the human response to that reminder, signifying a reciprocal interaction between the divine and human. Muslims believe the prophets deliver God's message as a reminder to humans, who, in turn, should remember and acknowledge it.

Several verses in the Quran emphasize the importance of remembering the will of God by saying phrases such as "God willing" "God knows best," and "If it is your will.' This is the basis for dhikr. Surah al-Kahf (18), Ayah 24 states a person who forgets to say, "God willing", should immediately remember God by saying, "Maybe my Lord will guide me to [something] more akin to rectitude than this." Other verses include Surah al-Ahzab (33), Ayah 41, "O you who have faith! Remember Allah with frequent remembrance", and Surah ar-Ra'd (13), Ayah 28, "those who have faith, and whose hearts find rest in the remembrance of Allah. Look! The hearts find rest in Allah's remembrance!"

Sufi dhikr most commonly involves the repetition of the Names of Allah. This practice is central to Sufi spiritual exercises and is intended to foster a deeper connection with the Divine. The Names of Allah, also known as Asma'ul Husna, represent various attributes of God, such as "Ar-Rahman" (The Most Merciful) and "Al-Karim" (The Generous). By invoking these names, practitioners aim to internalize the qualities they represent, cultivate a state of spiritual purity, and draw closer to God. The repetitive nature of dhikr helps to quiet the mind, focus the heart, and create a sense of inner peace and presence. To Sufis, dhikr is seen as a way to gain spiritual enlightenment and achieve annihilation of self (fana) to seek permanence in God. All Muslim sects endorse individual rosaries as a method dhikr and meditation, the goal of which is to obtain a feeling of peace, separation from worldly values (dunya), and, in general, strengthen Iman (faith). The main purpose of dhikr is to fill the heart with spiritual meaning and not simply chant the invocations with an empty heart and absent mind. When performed with awareness, the heart then becomes receptive to the activity of the tongue and is aware of God's presence.

There are numerous conventional phrases and expressions invoking God.

Reciting the Quran sincerely is also considered a kind of Dhikr. For example:

"It is truly I. I am Allah! There is no god [worthy of worship] except Me. So worship Me [alone], and establish prayer for My remembrance" — Surah Taha, Ayah 14

"O believers! Always remember Allah often" — Surah Al- Ahzab, Ayah 41