Please explain the concept of Qadr (Taqdeer)?

Answer

Even on the Day of Qiyaamah, even the Ambiya (Alayhis salaam) will not fully understand Qadr. It is impossible for the created human mind with its finite and limited understanding to comprehend Qadr which is related to the Eternal Attributes of Allah Azza Wa Jal. Shaitaan uses this topic to weaken a person's Imaan, hence Rasulullah (Sallallahu alayhi wasallam) vehemently forbade the Sahaabah from attempting to probe Qadr.