Hadith.1623 - Muhammad ibn Khalid al-Barqi wrote to Abu Ja'far al-Thani, Imam Muhammad al-Jawad (as) asking:
"Is it permissible to pay the Zakat due on crops such as wheat and barley, or on gold, in dirhams equal to their value, or is it obligatory to pay the Zakat in kind from each category?"
Imam (as) replied: "Whichever is easier may be given."