Reference: al-Hilyah – Volume 5, Page 224
Bilaal ibn Sa’d said:
The remembrance of Allaah is [of] two [types]:
i) The remembrance with the tongue, and that is good and beautiful;
ii) The remembrance of Allaah with respect to that which He has permitted (halaal) and [that which He has] prohibited (haraam), and this [type of remembrance] is the best.