It is narrated from Abdullah bin Amr (may Allah be pleased with them both) that when spoils came to the Messenger of Allah (peace and blessings be upon him), he (peace and blessings be upon him) would order Bilal (may Allah be pleased with him), who would announce it among the people; they would then bring their spoils, and he (peace and blessings be upon him) would take out the khumus from it and distribute it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12861