What is the ruling on delivering admonitions at gravesides after the deceased has been buried, gathering people to hear them, and utilizing this as an opportunity for da'wah in countries where preachers face restrictions?

Preaching before burial is permissible sometimes, especially if the burial is delayed, as it has been authentically reported that the Prophet, peace and blessings be upon him, preached at the grave.

Among these instances is what Al-Bara' bin 'Azib, may Allah be pleased with him, narrated: "We were with the Messenger of Allah, peace and blessings be upon him, at a funeral. He sat at the edge of the grave and wept until the soil became wet, then he said: 'O my brothers, prepare for something like this.'"

Likewise, what Ahmad and Abu Dawud narrated from Al-Bara' bin 'Azib: "We went out with the Prophet, peace and blessings be upon him, for the funeral of a man from the Ansar. We reached the grave, and it had not yet been dug. The Messenger of Allah, peace and blessings be upon him, sat down, and we sat around him, as if birds were on our heads. In his hand was a stick with which he was poking the ground. He raised his head and said: 'Seek refuge with Allah from the torment of the grave' - twice or thrice - then he said: 'Indeed, when a believing servant is in cessation from this world and approaching the Hereafter, angels with white faces descend upon him from the sky...'"

As for constant preaching at the grave, Sheikh Ibn 'Uthaymin was asked about it and said that it is contrary to the Sunnah, because it was not practiced during the time of the Prophet, peace and blessings be upon him.

He said: What was reported from the Prophet, peace and blessings be upon him, were merely words, not a sermon, and making preaching at the grave a regular custom is not from the custom of the Salaf, and it might be an exaggeration (tannatu'), because the occasion is one of humility and tranquility, not one of rousing emotions.

And Allah knows best.