On offering a collective dua after burial

Question: What is the ruling on offering a collective dua after burial?
Answer: This practice is not found in the established Sunnah. The Sunnah-prescribed prayer for the deceased is the Janazah prayer. It is preferable to leave soon after the burial. At that time, the deceased’s child or a close righteous person may pray for the deceased’s steadfastness.
The grave may be visited after the likely time of questioning the deceased has passed. Dua may also be offered at that time.
Answered by: Allama Mufti Ubaidur Rahman Khan Nadwi
Source: Jame-ul-Fatawa, Encyclopaedia of Islamic Fiqh and Fatwas