The Book of Zakat (Kitab Al-Zakat)
Muslim :: Book 5 : Hadith 2180
Thauban reported Allah's Messenger (may peace be upon him) as saying: The most excellent dinar is one that a person spends on his family, and the dinar which he spends on his animal in Allah's path, and the dinar he spends on his companions in Allah's path. Abu Qilaba (one of the narrators) said: He (the narrator) started with family, and then Abu Qilaba said: Who is the person with greater reward than a person who spends on young members of his family (and thus) preserves (saves them from want) (and by virtue of which) Allah brings profit for them and makes them rich.