What is the meaning of seeking forgiveness (istighfar), how is it performed, and what are its benefits? Are there specific times for it? Is it permissible to repeat "Astaghfirullah" (I seek forgiveness from Allah) 500 times daily, and is this the correct way to seek forgiveness? And what is the meaning of the Prophet, peace and blessings be upon him, seeking forgiveness 100 times a day?

Seeking forgiveness (Istighfar) is permissible at all times. However, it is prescribed to specify times that are established by religious law, such as the pre-dawn hours, after prayers, and in the morning and evening, to avoid falling into the innovation of addition (bid'ah idafiyyah). The heart must be present during seeking forgiveness and other acts of worship, because a supplication from an unmindful, heedless heart is not answered. There is no harm in seeking forgiveness while busy, because remembrance without the presence of the heart is better than abandoning it altogether.