Qur’an, Sura Al Fath, Chapter 48
8. Truly, We have sent you (O Muhammad) as a witness and a bringer of good news and as a warner.
9. So that you (people) may believe in Allah and His Messenger, and may honor Him, and may revere Him, and do tasbih [continuous glorification] of Him in the morning and late afternoon.
10. Surely, those who give allegiance (and promise) to you (O Muhammad) actually they give their allegiance to Allah. The hand of Allah is above their hands. So whoever breaks their oath breaks it only to hurt themselves. While whoever keeps the covenant they made with Allah, He will give them a tremendous reward.
bay’at: pledge or promise of allegiance; initiation into a Sufi order
tasbih: glorification through repeating the names of Allah
zikr: mentioning Allah’s name repeatedly with certain intention and contemplation; glorification or supplication; reminder