Amir al-Sha'bi (may Allah have mercy on him) says: The Prophet (peace and blessings be upon him) had a share called al-safi (the chosen portion); if he wished a slave, a slave-girl or a horse, he would choose it before the khumus (one-fifth).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12751