The following fifteen things are wajib in salaat. If you forget to perform any one of these things during namaz your namaz will be incomplete and you will have to perform sajdah sahw. If you leave off performing a wajib on purpose, then you will be a sinner and the entire salaat will have to be repeated.
- To begin the namaz with the special words “Allahu Akbar”
- To recite surah Fatiha in the first two rakaats of the fard namaz and in every rakat of witr and nafil namaz.
- To add a small sura or three short ayats to surah fatiha in the first two rakaats of a fard namaz and all rakaats of witr and nafil.
- To recite sura fatiha before the small surah or ayats.
- To do the second prostration after the first prostration without any gap in-between.
- To perform all fard actions in namaz in a slow calm manner.
- To sit in the first sitting long enough to say tashahhud.
- To recite the tashahhud in the first and last sittings.
- To stand for the second rakat quickly after finishing the tashahhud and not rest or delay.
- To exit from the namaz by using the words of salaam twice.
- To recite the qunoot in witr after the reciting of sura fatiha and the second sura.
- The extra takbeers in the two eid namaz.
- To say the takbirs of ruku in the second rakat in the two eid namaz.
- To recite the qirat loud in fajr and the first two rakaats of maghrib, isha, jumah, the two eids, tarawih and witr in ramadhan.
- To recite the qirat silently in zuhr, asr, the third rakat of maghrib and the third and fourth rakat of ishaa, and all nafl salaats during the day.
The one praying alone has the choice of reciting loud or silently in the fard prayers. It is better to pray loudly as it is closer to the actual way the salaat is to be performed.