Zakat (Kitab Al-Zakat)
Dawud :: Book 9 : Hadith 1604
Narrated Awf ibn Malik:
The Apostle of Allah (peace_be_upon_him) entered upon us in the mosque, and he had a stick in his hand. A man hung there a bunch of hashaf. He struck the bunch with the stick, and said: If the owner of this sadaqah (alms) wishes to give a better one than it, he would give. The owner of this sadaqah will eat hashaf on the Day of Judgment.