I want to know the different between Qabli and Baadi when u ar observing prayers? In elaborate form.
The concept of Qabli and Ba’di relates to the Sajda al-Sahaw (the prostration in recompense for the errors committed).
To read about the Sajda al-Sahaw please look at one of the earlier answers: How to Amend Mistakes during Prayers?
As for what is known as Qabi and Ba’di, this refers to whether this Sajda needs to be performed before the Salam (Qabli) or after the Salam (Ba’di).
There is no consensus about this and the main schools of thought of Fiqh differ about it:
- Hanafis consider it to be always after the Salam, but assert that if it is done by mistake before the Salam then it is acceptable.
- Shaf’is consider it to be always before the Salam, but assert that if the Salam is said by mistake and not much time has passed after it then it can be said after the Salam.
- Malikis distinguish between a mistake that relates to adding something to the required elements of prayer (like reading an extra Rak’ah) or reducing from the required elements of prayer. In case of adding they consider the position of the Sajda to be after Salam. In case of reducing (and also in case of reducing something and adding something else) they consider the position of the Sajda to be before Salam.
- Hanbalis consider both positions (before or after Salam) to be valid, while for most cases consider doing the Sajda before Salam to be more rewarding.
- Jafaris (Imami Shia) consider it to be only permissible after Salam.
As you can see from the above, there is no consensus about Qabli and Ba’di. This is because this issue (doing Sajda Sahaw before or after Salam) has not been covered by the Sunnah of the Prophet (pbuh) which means it is a matter of Ijtihad and opinion and people can have different views or may follow different views about it and within reason, none can be considered as wrong.
Also if you look at the Ahadith that are used for determining whether to do Qabli or Ba’di, you may come to agreement with me that none of these Ahadith suggest that only Qabli or only Ba’di can be performed for a particular mistake in prayers:
A Qabli reported from the Prophet (pbuh):
Ibn Buhaynah says that once the Prophet (sws) led our zuhr prayer but did not sit down after the first two rak‘at and stood up for the third rak‘at. People also stood up with him until the time when the prayer was about to end and the people were waiting for the salam to be said, the Prophet (sws) uttered the takbir and before saying the salam offered two prostrations and then said the salam. – Bukhari – 1224
A Ba’di reported from the Prophet (pbuh):
It is narrated by Ibn Mas‘ud (rta) that once when the Prophet (sws) led the zuhr congregational prayer, he prayed five rak‘at. He was asked: “Has the prayer been lengthened?” He replied: “What happened?” The people declared that he had prayed five rak‘at. At this, the Prophet (sws) turned his feet while sitting and faced the qiblah and then offered two prostrations and then said the salam. – Bukhari – 401
It seems like some scholars, after analyzing Ahadith like the above, have arrived at an understanding that it is “reduction by mistake” versus “addition by mistake” that determines whether to do Qabli or Ba’di. However (appreciating that the Sunnah has not instructed us about Qabli or Ba’di) then what simply can be derived from the above two Ahadith is nothing but the common sense, that is, do the Sajda before Salam if you realized your mistake before Salam, and after Salam if you realized your mistake after Salam, as simple as that.