How exactly do you pray Salaat At-Tawbah? I have seen your other fatwas, but I do not know what you say during this specific prayer. When do you supplicate? During the prayer? If so, then when during the prayer? Also, do we generalise in the supplication? Is it a specific supplication that we say? How many times do we say it? How long should the prayer be? When can you pray it?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger. 

If by Salat At-Tawbah, you mean the two Rak’ahs (units of prayer) that a person performs after having committed a sin, then Imaam Ahmad and Abu Daawood in reported As-Sunan that ‘Ali said:

“I was a man who, when I would hear a narration from the Messenger of Allaah Allaah would benefit me with it as much as He willed. But when one of his Companions narrated a narration to me, I urged him to swear by Allaah as to its truthfulness. If he swore to me, then I would believe him. Abu Bakr narrated a narration to me, and Abu Bakr is truthful. He said, 'I heard the Messenger of Allaah say, 'There is no slave (of Allaah) who commits a sin and then performs ablution well and stands and prays two Rak'ahs and seeks the forgiveness of Allaah except that Allaah forgives him. He then recited this verse: {And those who, when they commit an immorality or wrong themselves [by transgression], remember Allaah and seek forgiveness for their sins - and who can forgive sins except Allaah? - and [who] do not persist in what they have done while they know.}'' [Quran 3:135]”

Scholars call this prayer Salat At-Tawbah, and it is recommended.

The Fiqh Encyclopedia reads, “The prayer of repentance is desirable according to the agreement of the Four Schools of Fiqh...”

As regards the manner of performing it and what is said in it, then it is like all other prayers that are prayed in two Rak’ahs in its manner, its Athkaar (plural of Thikr [expressions of remembrance of Allaah]) and what is said in it; such as the prayer of salutation of the masjid (Tahiyyat Al-Masjid), the Sunnah of ablution [i.e. praying two Rak’ahs after having performed ablution], or other Sunan. It does not have a special Thikr, a specific number of supplications, or a given length of time in performing it. So it is two Rak'ahs like all other prayers that are prayed two Rak'ahs. One supplicates in Sujood (prostration) like all other prayers and seeks the forgiveness of Allaah with any formula of forgiveness, such as saying Astaghfirullaah (I seek the forgiveness of Allaah), Allaahumma ighfir lee (O Allaah forgive me), or the like. Some scholars are of the view that what is meant by forgiveness in the hadeeth is repentance. Tuhfatul-Ahwathi reads, “Then he seeks the forgiveness of Allaah, and what is meant by forgiveness is repentance by regretting the sin, ceasing to do it, being determined to never return to it again, and give back the rights of the people, if any…”

Concerning its time, i.e. when to pray it, then it does not have a special time; rather, it is legislated to perform it after having committed a sin. So it is a prayer that has reasons for performing it, so it can be performed at any time, even after the ‘Asr prayer.

Shaykh Ibn Taymiyyah said:

“The prayers with reasons [i.e. which have reasons to be performed even at the time at which it is prohibited to pray], all of them cannot be performed if they are delayed until after the time of prohibition has expired [i.e. they should be performed even during the time of prohibition, and if one delays them until this time is finished, then the reason for performing them has elapsed]; examples include the prostration of the recitation of the Quran (Sujood Tilaawah), the prayer of salutation to the mosque (Tahiyyat Al-Masjid), the eclipse prayer (Salat Al-Kusoof), and the prayer after having performed ablution as in the hadeeth of Bilaal. The same thing applies to the guidance-seeking prayer (Istikhaarah) if the matter upon which the person seeks Istikhaarah will be missed if he delays the (Istikhaarah) prayer. The same also applies to the prayer of repentance, which is immediately obligatory because it is desirable for the person to pray two Rak’ahs and then repent…”

Allaah knows best.