MISSED (QAZA) NAMAAZ
'So curse be to those offering salaah'
'Who are neglectful of their salaah'
(Surah Ma'oon. verse 4,5)
These verses were revealed regarding the hypocrites, who would sometimes perform Namaaz with total lack of devotion and love, not out of belief, but in order to show the believers.
Verse 4 mentions a word 'wail', which is a valley in Hell. And this is for those who miss Namaaz deliberately. (Bahar e Shariyat)
Prophet Muhammad ﷺ said that verse 5 is for those who perform Namaaz after their prescribed times. (Sunanil Kubra lil Baihaqi)
The Namaaz performed after the prescribed time is called missed (qaza), and to miss Namaaz without a convincing and justifiable (according to Islamic laws [shariya]) reason is a severe sin (gunah e kabeera). The sin is not forgiven when simply the Namaaz is performed later. In addition to performing qaza, it is necessary to repent (seek forgiveness from Allah Ta'ala). Namaaz cannot be performed on behalf of someone else. Also, compensatory money (fidyah) cannot be given to poor as a substitute for Namaaz for a person who is seriously ill or very old.
It is farz to make qaza of a farz, and it is wajib to make qaza of a wajib.
Ada is performing Namaaz in its prescribed time.
I'aadah is performing a Namaaz for the second time before its time is over. (Repeating a Namaaz).
When performing the farz and Witr of daily Namaaz, and when making qaza of them, it is necessary to observe the 'order of time' (tarteeb). The 'order of time' is necessary for qaza and ada Namaaz as long as they are less than six-missed Namaaz. The qaza must be performed first and then ada e.g. if someone has missed Fajr, Zohr, Asr and Magrib, then he cannot perform the Isha Namaaz until he performs the qaza of the four Namaaz in a sequence.
If someone misses his Fajr Namaaz, and he performs qaza of it before zawaal on the same day, then he must perform qaza for both sunnat and farz of the Fajr Namaaz.
When the number of qaza Namaaz equals six, then the 'order of time' (tarteeb) is not necessary. However, the necessity of 'order of time' also ceases when there is not enough time to perform all qaza and the ada Namaaz.
Tabrani and Ibne Umar(Radi Allaahu Anhu) report from Hazrat Umar(Radi Allahu Anhu) that Prophet Muhammad ﷺ said, 'that a person who forgets to perform any Namaaz, and he only remembers at the time when he is behind the imaam, then he should complete this Namaaz, and then he should perform the Namaaz he had forgotten.
Prophet Muhammad ﷺ said, 'If anyone misses his Namaaz due to sleep or forgetfulness, he must perform the qaza Namaaz when he remembers it'. (Muslim)
When you think someone sleeping has forgotten to perform his Namaaz, it is wajib to wake him up and make him aware of it. (Bahar e Shariyat, Raddul Muhtar)