One must continue and purify oneself by continuing.
Know that, according to the Naqshbandis, the first dhikr (dhikr, remembrance of God) formula is the utterance of the name Allah while contemplating its meaning; according to the Shadhilis, it is the phrase Lā ilāha illā Allah (There is no god but Allah). These two forms of dhikr, as well as istighfār (seeking forgiveness) and prayer, are performed in other tariqas (tariqa, Sufi paths/orders) too, with serenity of heart and complete decorum. (Jāmiʿ, 17)
Ādāb of dhikr (the etiquette of dhikr) is as follows: The person who will perform dhikr first performs ablution, then, according to some Sufis, prays two rakʿas. In the first rakʿa, s/he recites Sūrat al-Kāfirūn; in the second rakʿa, Sūrat al-Ikhlāṣ.