"A dead person does not bear greater hardships in his/her grave at any time than the first night."
Prophet Muhammad (S.A.W.)
On the day of burial it is recommended to give sadaqa, asking for rahma (mercy) for the marhum/marhuma.
In addition as a gift, one should pray Salatul Wahshat if one is a near relation or Salatul Hadiya Mayyit with the niyya of pleasing Allah and seeking forgiveness for the dead person.
Wahshat means loneliness and anxiety. This salaa can be recited at any time during the first part of the night of burial, but it is better to pray it at the beginning of the night after Isha salaa.
It consists of 2 rakaats.
In the 1st rakaat after Suratul Hamd recite Ayatul Kursi (2:254, 255, 256)
In the 2nd rakaat after Suratul Hamd recite 10x Suratul Qadr
Hadiya Mayyit means a gift to the mayyit. The salaa consists of 2 rakaats.
In the 1st rakaat after Suratul Hamd recite Suratul Qadr
In the 2nd rakaaat after Suratul Hamd recite Suratul Kawthar.
After completing the salaa, ask Allah to send the thawabs of the salaa to the grave of the marhum/marhuma.