لِلَّذِينَ لَا يُرِيدُونَ عُلُوًّا فِي الْأَرْضِ وَلَا فَسَادًا (We assigned it to those who intend neither haughtiness on earth nor mischief. - 28:83). This verse tells us that only those will achieve salvation and success in the Hereafter who do not intend any mischief, nor are indulged in عُلُوًّا ` Uluww in this world. عُلُوًّا ` Uluww means pride or conceit, that is, to present oneself as superior before others, and to look down upon others and treat them in an insulting manner. Mischief is used here for oppression. (Sufyan Ath-Thauri). Some commentators have observed that every sin is a 'mischief in the world', because the nuisance of the sin curtails the blessings of the world. This verse tells us that those who intend to do cruelty and feel proud, or commit sin have no share in the Hereafter.
Arrogance and conceit as condemned in this verse, is the behavior in which one shows off as being superior, and looks down upon others. Otherwise to strive for oneself a good dress, a good house, and good food, when it is not intended to show off, is no sin, as reported in a hadith in Sahih Muslim.
Firm intention to commit a sin is also sin
It is clarified in this verse that the intention for mischief and pride will debar one from the share of Hereafter. It is, therefore, clear that the firm intention of a sin is as much a sin. (Ruh) However, if one changes his mind for fear of Allah, then a reward is noted in his record instead of sin. But if he fails to act on that sin, due to reasons beyond his control, while he had firm intention to act upon it, then the sin stays against his name, and will be recorded as such. (Ghazzali)
The last verse وَالْعَاقِبَةُ لِلْمُتَّقِينَ (And the (best) end is for the God-fearing - 28:83) elaborates that it is not enough to abstain from mischief and pride to get the share of the Hereafter, but following the righteous path is as much a requirement. To follow all the religious obligations is also essential for the salvation in the Hereafter.