What is prescribed for those present at the grave to do immediately after the deceased has been buried?

It is from the Sunnah to supplicate for the deceased after burying them and leveling the earth over them, due to what was reported from Uthman (may Allah be pleased with him) that when the Prophet (peace and blessings of Allah be upon him) finished burying the dead, he would stand over the grave and say: "Ask forgiveness for your brother and ask for him steadfastness, for indeed, he is now being questioned."