Which adhkar are mustahab and which are fard. I would like to know that which adhkar are fard and which are mustahab. Please if you could elaborate the answer.
Most adhkar are mustahab. Fard ones are those said in Salah, Adhaan, Talbiyah, Takbirat al-Tashriq, replying to Salam, saying Tasmiyah on slaughtering cattle etc.
Remembering Allah, may He be exalted, may be obligatory, as in the case of takbeerat al-ihram (the takbeer said when starting the prayer), or it may be mustahabb.
Dhikr may be obligatory; obligatory adhkaar include some of the adhkaar of the prayer, such as takbeerat al-ihraam and recitation of Qur’an. Obligatory adhkaar also include the adhaan and iqaamah, according to the view that they are a communal obligation (fard kifaayah). Returning greetings of salaam, and saying Bismillah when slaughtering an animal for meat are also obligatory adhkaar.