Short answer
The Prophet ﷺ said the best dhikr is La ilaha illallah. He also named four phrases as the most beloved words to Allah: Subhanallah, Alhamdulillah, La ilaha illallah and Allahu Akbar. Subhanallahi wa bihamdihi, Subhanallahil Azim are two phrases light on the tongue and heavy on the scale.
Dhikr (remembrance of Allah) is mustahabb at all times. Reciting the Quran is the greatest form of dhikr in general, but the specific adhkar the Sunnah sets for a time, such as after salah or in the morning and evening, are better in their time than recitation.
The four schools agree on this.
Explanation
Dhikr means remembering Allah, with the heart and the tongue. The Quran says hearts find rest in it (13:28) and tells the believers to remember Allah much (33:41). The Prophet ﷺ compared the one who remembers his Lord and the one who does not to the living and the dead.
The phrases with the greatest reward in authentic hadith:
- La ilaha illallah (there is no god but Allah): "The best dhikr is La ilaha illallah, and the best dua is Alhamdulillah" (al-Tirmidhi).
- The four: Subhanallah, Alhamdulillah, La ilaha illallah, Allahu Akbar, "the most beloved words to Allah" (Muslim). See the tasbih of Fatimah.
- Subhanallahi wa bihamdihi, Subhanallahil Azim: two phrases light on the tongue, heavy on the scale, beloved to the Most Merciful (Bukhari).
- The dhikr of Juwayriyah: Subhanallahi wa bihamdihi, adada khalqihi, wa rida nafsihi, wa zinata arshihi, wa midada kalimatihi. The Prophet ﷺ told her these words, said three times, outweighed all she had said since dawn (Muslim).
- Astaghfirullah and salawat on the Prophet: see Sayyidul Istighfar.
The best dhikr for you is also the one you keep up. A few minutes after each salah with the adhkar after salah, and the morning and evening adhkar, build a strong habit. You can count on your fingers or with a tasbih counter. The four schools agree on the virtue of these phrases. Read more in the dhikr guide.
The evidence
Quran, Surah Ar-Ra'd 13:28
ٱلَّذِينَ ءَامَنُوا۟ وَتَطْمَئِنُّ قُلُوبُهُم بِذِكْرِ ٱللَّهِ ۗ أَلَا بِذِكْرِ ٱللَّهِ تَطْمَئِنُّ ٱلْقُلُوبُ ﴿٢٨﴾
Those who have believed and whose hearts are assured by the remembrance of Allah. Unquestionably, by the remembrance of Allah hearts are assured."
Dhikr brings rest to the heart.
Quran, Surah Al-Ahzaab 33:41
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ ٱذْكُرُوا۟ ٱللَّهَ ذِكْرًۭا كَثِيرًۭا ﴿٤١﴾
O you who have believed, remember Allah with much remembrance
Believers are commanded to remember Allah often.
Jami' at-Tirmidhi 3383
Grading to be checked... أفضل الذكر لا إله إلا الله وأفضل الدعاء الحمد لله ...
"The best dhikr is La ilaha illallah, and the best dua is Alhamdulillah."
Names the best phrase of remembrance.
Sahih al-Bukhari 6406
Sahih... كلمتان خفيفتان على اللسان ثقيلتان في الميزان حبيبتان إلى الرحمن ...
"Two phrases are light on the tongue, heavy on the scale and beloved to the Most Merciful: Subhanallahi wa bihamdihi, Subhanallahil Azim."
A short dhikr with great weight.
Sahih Muslim 2726
Sahih... سبحان الله وبحمده عدد خلقه ورضا نفسه وزنة عرشه ومداد كلماته ...
"Glory and praise be to Allah, as many as His creation, as much as pleases Him, as heavy as His Throne, and as much as the ink of His words."
A dhikr that outweighs hours of other remembrance.
Sahih al-Bukhari 6407
Sahih... مثل الذي يذكر ربه والذي لا يذكر ربه مثل الحي والميت ...
"The one who remembers his Lord and the one who does not are like the living and the dead."
Shows the worth of dhikr in a believer's life.
Where the ruling is recorded
- Radd al-Muhtar (Ibn Abidin), Kitab al-Salah, discussion of the adhkar after the obligatory prayer. Recitation of the Quran is better than dhikr except where a specific dhikr is reported for the time.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.