Abu Dawud
Zakat
Book Number: 003 / Hadith Number: 1679
Narated By Abdullah ibn Amr ibn al-'As : The Prophet (pbuh) said: There are forty characteristics; the highest of them is to give a goat on loan (for benefiting from its milk). If any man carries out any of those characteristics with the hope of getting a reward and testifying to the promise for it, Allah will admit him to Paradise for it.