Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.099.

Section : Making (Qada') for missed salah.The scholars agree that it is obligatory for one who has forgotten the salah or slept through its time to make up the missed [qada') prayer. This opinion is based on the hadith of the Prophet mentioned earlier: "There is no negligence while one is asleep but forgetfulness occurs … Continue reading Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.099.

Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.099A.

Section : In law, there is no way for one who leaves a salah intentionally to make its qada'.He may however, resort to increasing his voluntary and supererogatory acts. Ibn Hazm has thoroughly discussed this question. The following is a summary of what he says on this subject:Concerning one who leaves a salah intentionally until … Continue reading Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.099A.