True Zikr is to fulfil the command of Allah Ta’ala, which is directed to us at a particular time—to perform Salaah in its respective time, to pay Zakaah when due, to fast during the month of Ramadaan, to perform Hajj at the time of Hajj (if one has the means), etc.
When a person’s parent, wife, child, neighbour, etc., is very ill and requires medication to be brought from the pharmacy as a matter of urgency, then at that time, true Zikr is to postpone all optional Ibadah and attend to the need.
Ruqayya (radiyallahu ‘anha), the beloved daughter of Rasulullah (sallallahu ‘alayhi wa sallam), was very ill when the call for Badr was suddenly made. Since only 313 companions were accompanying Rasulullah (sallallahu ‘alayhi wa sallam), there was a definite need for Uthman (radiyallahu ‘anhu), the husband of Ruqayya (radiyallahu ‘anha), to also join the expedition. However, Rasulullah (sallallahu ‘alayhi wa sallam) left him behind to care for his wife during her severe illness.
True Zikrullah is the fulfilment of the commands of Allah Ta’ala and Rasulullah (sallallahu ‘alayhi wa sallam)