1. If one does not have the means to reciprocate the gift that he had received, then one should thank the person giving the gift by saying, “Jazaakallah khairan (May Allah Ta‘ala reward you with the best of rewards)”. Similarly, one should make dua for him/her.
عن أسامة بن زيد قال قال رسول الله صلى الله عليه وسلم من صنع إليه معروف فقال لفاعله جزاك الله خيرا فقد أبلغ في الثناء (سنن الترمذي، الرقم: 2035)
Hazrat Usaamah bin Zaid (radhiyallahu ‘anhu) reports that Rasulullah (sallallahu ‘alaihi wasallam) said, “The one who has received some good from someone (or has received a gift), then he should say to the person, “Jazaakallah khairan (May Allah Ta‘ala reward you with the best of rewards).” By doing so, he has praised the person and honoured him greatly (and fulfilled the right of gratitude to him).”
عن جابر بن عبد الله، قال: قال رسول الله صلى الله عليه وسلم: من أعطي عطاء فوجد فليجز به، فإن لم يجد فليثن به، فمن أثنى به فقد شكره، ومن كتمه فقد كفره (سنن أبي داود، الرقم: 4813)
Hazrat Jaabir (radhiyallahu ‘anhu) reports that Rasulullah (sallallahu ‘alaihi wasallam) said, “When a person receives a gift from someone, if he has the means to give the person a gift in return, then he should do so. If he does not have the means to reciprocate by giving a gift, then he should make dua for him and speak good of him, as the one who makes dua and speaks good of the person has expressed gratitude to him for the favour he received from him, and the one who conceals it (i.e. he does not reciprocate the gift nor does he make dua and speak good of the person), then such a person has showed ingratitude.”
عن أنس، قال: لما قدم النبي صلى الله عليه وسلم المدينة أتاه المهاجرون فقالوا: يا رسول الله، ما رأينا قوما أبذل من كثير ولا أحسن مواساة من قليل من قوم نزلنا بين أظهرهم لقد كفونا المؤنة وأشركونا في المهنإ حتى لقد خفنا أن يذهبوا بالأجر كله. فقال النبي صلى الله عليه وسلم: لا ما دعوتم الله لهم وأثنيتم عليهم (سنن الترمذي، الرقم: 2487)
Hazrat Anas (radhiyallahu ‘anhu) reports that on one occasion, the Muhaajireen came to Hazrat Rasulullah (sallallahu ‘alaihi wasallam) and said, “O Rasulullah (sallallahu ‘alaihi wasallam), the Ansaar have taken all the rewards. They are such that at the time when they possess a lot, they are extremely generous, and when they possess a little, they share the little they have with others. They have fulfilled all our needs (and we do not have the means to reciprocate their generosity upon us).” Rasulullah (sallallahu ‘alaihi wasallam) replied, “No, (they will not take all the rewards, but you will also receive rewards) if you continue to make dua for them, praise them and speak good of them before others.”