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 Referenceمعجم صغير للطبراني / كتاب الادب / 745
Hadith Gradingمحدثین:حديث صحيح
Hadith Takhrij«حديث صحيح، وأخرجه ابن حبان فى «صحيحه» برقم: 3413، والنسائي فى «الكبریٰ» برقم: 9937، والترمذي فى «جامعه» برقم: 2035، قال الشيخ الألباني: صحيح ، والبزار فى «مسنده» برقم: 2601، والطبراني فى «الصغير» برقم: 1183، والضياء المقدسي فى «الأحاديث المختارة» برقم: 1321، 1322»
´Usamah bin Zaid narrated that the Messenger of Allah (s.a.w) said:` "Whoever some good was done to him, and he says: 'May Allah reward you in goodness' then he has done the most that he can of praise."
Shaykh Dr. Abdur Rahman Freywai
Explanation: 1: That is, if someone has done a favor to another, and the recipient says to his benefactor, "Jazak Allahu khayran," then he has fully expressed gratitude for that favor.
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 2035
Narrated Usama bin Zaid (RA): Allah's Messenger (ﷺ) said. "If one is done a kindness and [expresses his gratitude] to his benefactor by saying 'May Allah give you a good reward', he has fully expressed his appreciation." [at-Tirmidhi reported it, and Ibn Hibban graded it Sahih (authentic)].