It is compulsory upon each and every adult Muslim male and female to perform Salaah. If a person started performing Salaah after a few years of his or her adult age, the balance of the Salaah due is compulsory upon him or her. For example: If Abdullah has become an adult at the age of 14, but at the age of 20 he started reading his Salaah, the balance of 6 years of Salaah is due on him. If the person does not remember the date of his adulthood, that person should consider 12 years as being their adult age. According to Islamic Fiqah, boys become adults at the age of 14 years.
If the female does not know when her adult age is, she can consider 9 years as being her adult age. Over and above she can further reduce her days by considering her monthly course period. Salaah is not compulsory in this time. In this way she can perform the balance of the Salaah that she had missed.
Each and every person should perform the balance of the Salaah immediately. Nobody knows when death will come or sickness and other work necessary in life. Salaah should be performed in time. Instead of performing Sunnat-e-Ghair- Muakkidah and Nawaafil Salaah, it is essential to perform the Salaah that are due. Instead of performing Nawaafil Salaah on important nights, it is better to perform the Salaah that are due. One must have hope on Almighty Allah that we will benefit from both the fard and Nawaafil Salaah together.
There are 20 Rakaahs of Fard Salaah in a day: Fajr (2), Zohar (4), Asr (4), Maghrib (3), Esha (4) and Witr (3). These Salaah can be performed any time accept during Zawaal, sunrise and sunset (During these period Salaah is Haraam). You should perform all balance of Salaah quickly without laziness. Nawaafil will not be accepted by Almighty Allah if the balance of the Salaah that have to be performed are still due.
When you stand to perform your due Salaah, you must say that you are performing the due Salaah for say, Fajr, for the sake of Allah, facing the Kaaba, Allahu-Akbar. The same way for the other Fard and Witr Salaah. If a perform has a lot of balance Salaah to be performed, then A’la Hazrat (radi Allahu anhu) has shown an easy way:-
In the Fard Salaah, while performing the 3rd and 4th Rakaah, instead of reading the Alhamdu Shareef, say Subhanallah 3 times and go for Ruku. This rule is only for the 3rd and 4th Rakaah of Fard Salaah. Witr must be performed fully.
While in Ruku and Sajdah, say only one time Subhana-Rabbi-al Azeem and Subhana-Rabbi-al A’la, saying these words properly.
While performing the Fard and Witr Salaah, after the At-tahiyat, say only Durood.
During Witr Salaah, instead of reading the Dua-e-Qunoot, say 3 times Rabbigh Firlee. (Fatawa Razvia, Vol.3, pages 621-2 & Al- Malfoozat Shareef, Vol.1, page 60-1)