Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) says that a man asked the Prophet (peace and blessings be upon him): I sacrificed before stoning. He (peace and blessings be upon him) said: "Stone, there is no problem." Another said: I shaved my head before slaughtering. He (peace and blessings be upon him) said: "Slaughter, and there is no harm."
Abu Bakr (al-Humaydi) said: Then I heard Sufyan being asked about this hadith, and Bulbul said to him: Is this among what you memorised from al-Zuhri, O Abu Muhammad? He said: Yes, as though you were hearing it from him, except that he used to narrate it at greater length; this is what I memorised of it. He said: And I heard Bulbul say to Sufyan: Abd al-Rahman bin Mahdi says that you told him: I did not memorise it. Sufyan said: Ibn Mahdi spoke the truth; I did not memorise it in its full length, but this part I have mastered.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9621