Supplicating to Allah (Subhaanahu wa Ta'ala) is in essence an act of Worship. Therefore, as in the case of all acts of Worship, your Prayers to Him must be sincere! Do not associate anyone or anything with Allah (Subhaanahu Wa Ta'ala) in your Prayers! Make sure you are free of show or the desire for reputation. The same is true in all other acts of worship.
Do not make Hajj so that it can be of you that you made Hajj. Do not be generous with your wealth so that it can be said of you that you are generous. Nor fast for the reputation of someone who fasts a lot.
If you long for a reputation or the people's praise, you are nullifying your deeds.
~ Taken from Page 43 “Whoever does you a favor” ~
On the authority of Usamah bin Zaid who said: “The Messenger of Allah said: Whoever does you a favor, say to him jazak Allahu Kair and (you) have shown your appreciation. (19)
On the authority of Shahru bin Hawshab who said, “I said to Umm Salamah, O Mother of The Believers, what du’a did The Messenger of Allah say the most when he was with you? She said , ‘He used to often say, “Oh Changer of hearts, establish my heart upon Your religion!”. (20)
(19. At-Tirmidhi) & (20. At-Tirmidhi)
There are many issues surrounding du’a. This hadith on the authority of Usamah bin zaid pertains to one of them. The Prophet said, “The Messenger of Allah said: Whoever does you a favor , say to him jazaka Allahu kair and (you) have shown your appreciation.
When someone does you a favor, such as helping you, giving you money or teaching you something, The Prophet commanded that you should repay that person. The compensation you extend will vary from situation to situation. For example, some people prefer rewarding a favor by returning the same or a little more than the same of what they received. Others prefer repaying a favor with du’a instead of monetary reward.
If a respected well to-do older person gives you a gift, repay them with a gift similar to the one they have given you. On the surface, what follows may appear to fall short of equaling the gift they’ve given you. However, making du’â equals and even surpasses any tangible gift a person of this stature can give you. "If you cannot find a suitable gift for them, then make du'a for them until they consider you have repaid them in full."
Saying Jazaka Allahu kair, whenever someone does you a favor or gives you something is payment enough. You have expressed your gratitude in the highest fashion. When Allah rewards a person with good, he or she receives happiness in this life and the next.