One of the fundamental tenets of Islam is that a person must found his whole life on the love and fear of Allah, and carry out all his obligations solely to win the good will and mercy of Allah and to attain His Paradise. In one verse, Allah tells believers: "Say: 'My prayer and my rites, my living and my dying, are for Allah alone, the Lord of all the worlds.'" (Surat al-An‘am: 162)
In the following verse, believers are told to live their religion solely for Allah, and not for any other purpose: "Except those who repent and put things right and hold fast to Allah and dedicate their religion to Allah alone; they are with the believers. Allah will give the believers an immense reward." (Surat an-Nisa': 146) Anyone who holds fast to Allah, knows that there is no other god than Allah, lives his life solely to gain His good pleasure, and never, ever abandons his faith in Him, shows he has true faith.
No sincere believer tries to gain the love, good will, praise of anyone other than Allah in his actions and religious duties. The finest examples of such sincere believers are the Prophet Muhammad (saas) and other prophets (peace be upon them all).
The Prophet (saas) sought only to win Allah's good pleasure, and spent his life striving to win His mercy, compassion and Paradise, with never a thought for personal interests or worldly gain.
Say: "I do not ask you for any wage for it, nor am I a man of false pretentions." (Surah Sad: 86)
Say: "I have not asked you for any wage - it is all for you. My wage is the responsibility of Allah alone. He is witness of everything." (Surah Saba': 47)