N A M A Z - E - W A H S H A T 
(PRAYERS TO BE OFFERED FOR THE DEPARTED SOUL ON THE NIGHT OF BURIAL)

It is MOST Important to Give Sadaqa on behalf of the deceased ON the FIRST Night of Burial .This has MANY beneifts & can only be achieved by giving sadqa on the first night when it is MOST needed by the deceased .

Sayyid Ibne Tawus has narrated from the Messenger of Allah (s.a.w.a.) that the most difficult for the dead person is the first night in the grave, so have pity on your dead ones and give Sadaqah on their behalf so that their difficulty is reduced and if there is nothing to give in Sadaqah you must pray two rakats prayer. 
Namaz Wahshat can be recited as under

645. It is befitting that on the first night after the burial of a dead person, two Raka'ats of wahshat prayers be offered for it. The method of offering this prayers is as follows: 
In the first Raka'at, after reciting Surah al-Hamd, Ayatul Kursi should be recited once and in the second Raka'at, Surah al-Qadr should be recited 10 times after Surah-al-Hamd;

and after saying the Salam the following supplication should be recited: Alla humma salli 'ala Muhammadin wa Ali Muhammad wab'ath thawabaha ila qabri ......(here the name of the dead person and his father's name should be mentioned). 

646. Wahshat prayers can be offered in the night following the burial of the dead body at any time, but it is better to offer it in the early hours of the night after 'Isha prayers. 

647. If it is proposed to transfer the dead body to some other town or its burial is delayed owing to some reason, the wahshat prayers should be deferred till the first night of its burial. 

Mullah Fateh Ali Sultaan Abadi relates that whenever he used to hear about the death of anybody, he would pray Salaatul Wahsha; the prayer recommended to be prayed for the deceased, and ask Allah to protect him especially in the first night in the grave from loneliness.

Well a certain man died and the Mullah prayed for him as was his custom. The Mullah met a friend of his who told him that he had seen the dead man in his dream, and was told that his condition had been miserable but when the Mullah prayed for him the torture was removed.

The dead man prayed for the Mullah for showing such consideration and kindness to him. (DAR UL SALAAM VOL 2 PAGE 315)

Another Prayer 
In the first rakat after Surah Hamd recite Surah Tawheed twice and in the second rakat after Surah Hamd recite Surah Takathur 10 times and after the Salaam say:  Allaahumma sale A'laa Muhammadinw wa aale muhammadin wab atha thawaabaha ilaa qabre dhaalikal mayyite f....alaan ibne falaan 

Thus the Almighty this very moment would send thousands of angels to the grave with heavenly garments and they turn the narrowness of the grave into vastness till the time the bugle would be blown and would make the good deeds of the worshipper shine like the sun and elevate him 40 grades. 

Fazilat/Merits  of Namaz-e-Wahshat 

Shaykh Thiqatul Islam Noori has narrated directly from Fath Ali Sultanabadi that he says he had the habit that whenever he heard of the death of a family member or a friend he would pray two rakats prayer of the night of burial and gift the Sawab. "No one knew about this practice of mine. One day I met a friend. He said: Last night I had a dream in which I saw a person who had died that day. I asked him about his well being and inquired about the conditions after death. He said that after my death I was in a terrible difficulty because my deeds were very bad. Till the time this person recited two rakat prayer. And he mentioned your name. This two rakat Namaz saved me from the punishment. May Allah have mercy on the parents of this person who did this favour to me.

It is narrated from Imam Sadiq (a.s.) that whenever there is narrowness and severity on the dead body the Almighty widens his grave and removes the narrowness and says that this widening is because you had recited Namaz-e-Wahshat for such and such believer brother.

Marhum Haaj Mulla said: At this time the person asked me what that prayer was? I explained to him the method of this prayer and those things that are beneficial to the dead ones. They are as follows: 
 

1. In order to be safe from the Wahshat-e-Qabr (terror of the grave) one should perform the ruku properly. Thus it is related from Imam Baqir (a.s.) that one who performs the ruku properly does not have terror in the grave. 
 

2. Recite "Laa ilaaha illallaahul Malikul haqqul Mubeen" a hundred times daily. One who recites this is safe from poverty and terror of the grave and affluence pulls him towards itself and the doors of Paradise open up for him. 
 

3. Recite Surah Yasin before going to bed. 
 

4. Recite Namaz-e-Lailatul Raghaib which is mentioned in the A'maal of Rajab on the eve of the first Friday of the month of Rajab.