Qays bin Muslim (may Allah have mercy on him) said: I asked al-Hasan bin Muhammad (may Allah have mercy on him) about this saying of Allah Almighty: "And know that whatever you take as spoils of anything, then indeed one-fifth of it is for Allah and for the Messenger" [Surah al-Anfal: 41]. He said: This is an opening of speech, (for) whatever is in this world and the Hereafter belongs to Allah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 12939