Abu Usamah said: I saw Salim bin Abdullah (may Allah have mercy on him) go down into the valley, then throw seven pebbles at the Jamrah, saying the takbir with each pebble: 'Allahu akbar, Allahu akbar' (Allah is the Greatest, Allah is the Greatest), "O Allah, make it an accepted Hajj, forgive the sins, and appreciate the deeds." I asked him about what he had said, and he said: My father (may Allah be pleased with him) told me that the Prophet (peace and blessings be upon him) used to stone the Jamrah from this very place, and every time he threw a pebble he would say the same as I have said.
Abdullah bin Hakim is da'if (weak). And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9550