Rasulullah Salallahu Alayhi Wasallam said: “He who does not thank people is unthankful to Allah.” [Abu Dawud]
Although Allah (subhana wa ta’ala) is the ultimate Bestower of all the good we receive, yet He commands us to thank the immediate source of the good too, the person or people through whom Allah (subhana wa ta’ala) sent the good to us. The people to whom we are most obliged during our lives, are our parents. Regarding them Allah (subhana wa ta’ala) says, “وَ:وَصَّيْنَا الْإِنسَانَ بِوَالِدَيْهِ حَمَلَتْهُ أُمُّهُ وَهْنًا عَلَىٰ وَهْنٍ وَفِصَالُهُ فِي عَامَيْنِ أَنِ اشْكُرْ لِي وَلِوَالِدَيْكَ إِلَيَّ الْمَصِيرُ “And We have enjoined on man (to be dutiful and good) to his parents. His mother bore him in weakness and hardship upon weakness and hardship, and his weaning is in two years give thanks to Me and to your parents, unto Me is the final destination”. [Al-Quran 31:14]
One of the early Muslims said: “Ingratitude for a kindness is one of the enormities (major sins). Gratitude consists of reciprocating it or supplicating for the person.” So, saying ‘Thank you’ is not enough. Allah (subhana wa ta’ala) in His mercy has guided us to an appropriate course of action to show gratitude. We should be genuinely grateful and if we are able to return the favour we should do so. Otherwise, or additionally, we should pray for the person who did the favour. You need no wealth to make dua for somebody, yet it fulfills your obligation of showing gratitude to the person who does you a good turn.
Source: Hadith app.