What is the ruling on one who is lazy in making up missed prayers or fasting?

If the reason for missing a prayer was sleep or unconsciousness, then it must be made up (qada'). However, if negligence was the cause, scholars have differed regarding the ruling on one who abandons prayer out of laziness: Some consider him a disbeliever, and he is not required to make up the prayers after repentance. Others, who are the majority, consider him a fasiq (transgressor) and oblige him to make up the prayers immediately, unless he does not know their number, in which case he should pray until he is reasonably certain that he has not missed any. It is advised to repent, increase in acts of obedience, and be diligent in performing prayers in congregation.