Hadith 745
Sayyiduna Usama bin Zaid (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings be upon him) said: "If someone does a favor to a person, and he says: «جزاک اللہ خیرا», then he has fully expressed his gratitude."
Hadith 746
Sayyiduna Abu Huraira (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings be upon him) said: "When a man calls his brother «جزاک اللہ خیرا», he has given him complete praise."
Hadith 747
Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him) in the same manner.