Sahih Al Bukhari Hadith Number 1401

Narrated Jarir bin `Abdullah: I gave the pledge of allegiance to the Prophet (peace be upon him) for offering prayer perfectly, giving Zakat, and giving good advice to every Muslim.

24  Obligatory Charity Tax (Zakat)
Hadith number 1401
Volume no 2
Chapter: 2 (To give Bai’a (pledge) for paying Zakat)