The Messenger of Allah ﷺ said, "Whoever has a kindness done to him and says to the one who did it, 'May Allah reward you with good,' has indeed offered the fullest praise."
قال رسول الله ﷺ: من صنع إليه معروف فقال لفاعله: جزاك الله خيرا، فقد أبلغ في الثناء.
Tirmidhi (2035) and Nasai in Amal al-Yawm wal-Layla (180) narrated it, Ibn Hibban graded it sahih (3413), and Diya in Mukhtarah (4/110) all narrated it through the route of Abu Jawwab Ahwas bin Jawwab, from Suayr bin Khams, from Sulayman Taymi, from Abu Uthman Nahdi, from Usama bin Zayd, who related it.Tirmidhi said, "This is a hadith that is hasan, good, and gharib. We do not know it from the hadith of Usama bin Zayd except through this route."I say, this is as he said, for in its chain are Suayr bin Khams and Ahwas bin Jawwab, and both of them make the hadith hasan.However, Tirmidhi said in Ilal (2/803), "I asked Muhammad about this hadith and he said, this is munkar, and Suayr bin Khams had few hadiths, and they narrate munkar reports from him." Abu Hatim said, "This is a munkar hadith with this chain." Ilal (2570).I say, perhaps the two of them mean by munkar that this hadith is something that Suayr bin Khams alone transmitted, and his being the sole transmitter does not harm it, for Ibn Main, Fasawi, and Daraqutni all deemed him trustworthy, and Tirmidhi said, he is considered reliable among the people of hadith. Abu Hatim said, "His hadith is acceptable, his hadith is written down but not relied upon as proof."As for the statement of Abu Hatim, "This hadith is, in my view, fabricated with this chain," Ilal (2197), its basis is not clear, for there is no one suspected of fabrication in its chain, and there is nothing in its text that is objectionable. Rather, it is corroborated by the hadith of Abu Hurairah, despite some weakness in it.And in the same meaning is what was narrated from Abu Hurairah, who said, the Messenger of Allah ﷺ said, "When a man says to his brother, 'May Allah reward you with good,' he has indeed given the utmost praise." Abdul-Razzaq (3118), Ibn Abu Shayba (27049), and Bazzar in Kashf Astar (1944) all narrated it through the route of Musa bin Ubayda, from Muhammad bin Thabit, from Abu Hurairah, who related it.Bazzar said, "We do not know of anyone who narrated from Muhammad bin Thabit except Musa bin Ubayda, and no one narrated this hadith from Abu Hurairah except him."I say, Muhammad bin Thabit, from whom Musa bin Ubayda narrates, is unknown, and Musa is daif.