I heard from a friend just recently that Qadā (missed out) prayers are not mentioned in the Holy Book or the Sunnah. If one has missed out his prayers earlier in life, one does not have to say his Qadā prayers. This means that Qadā-i-‘Umrī (prayers missed out in one’s previous life) as people often pray has no basis? Can you please clarify my confusion.
The Sharī‘ah is silent on the issue of missed prayers in one’s previous life. Scholars have formed different opinions on this issue. One group says that one must count each and every prayer missed out and then start offering it until they are completed. This is the view of some Hanafite jurists. Imam Ibn Taymiyyah is of the view that one should make a rough estimate of the missed out prayers and start praying them in place of praying sunnah or nafal rak‘āt. Imam Ibn Hazm holds the view that one does not need to offer the missed out prayers at all. Mere repentance is enough.
You can choose the opinion which appeals most to your intellect.