Sufyan bin Uyaynah (may Allah have mercy on him) said: Allah Almighty began the discourse on fay' and spoils by mentioning Himself, because it is the best of earnings, and every thing of honour and nobility is attributed to Him; and charity is not attributed to Him, because it is the dirt of people.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12938