مُسْنَدُ أَحْمَدَ
Musnad Ahmad 1368
Musnad 'Ali Ibn Abi Talib
It was narrated from "Ali (رضي الله عنه)... and he mentioned the same hadeeth, and said in it. The zakah of my wealth is forty thousand dinars.
Musnad Ahmad 1368lts isnad is Da'if like the report above]