It is narrated from Sayyiduna Adi bin Hatim (may Allah be pleased with him) that he asked the Messenger of Allah (peace and blessings be upon him), saying: O Messenger of Allah! Which charity is best? He (peace and blessings be upon him) said: "Providing the service of a slave in the path of Allah, providing the shade of a tent (in the path of Allah), or (in the path of Allah) giving a young she-camel ready for mating."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14327