Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.101.

Section : Zhikr as an Integral Part of Worship.

Sa’ id b. Jubair said, “Anyone engaged in obeying Allah is in fact engaged in the remembrance of Allah.” Some of the earlier scholars tied it to some more specified form. ‘Ata said, “The gatherings of zhikr are the gatherings where the lawful and the prohibited things are discussed, for instance, selling, buying, prayers, fasting, marriage, divorce, and pilgrimage.” Al-Qurtubi said, “Gatherings of zhikr are the gatherings for knowledge and admonition, those in which the Word of Allah and the sunnah of His Messenger, accounts of our righteous predecessors, and sayings of the righteous scholars are learned and practiced without any addition or innovation, and without any ulterior motives or greed.”