It is narrated on the authority of Ibn Abbas that the Messenger of Allah (peace and blessings of Allah be to him) transmitted from the Blessed and Great Lord: “Verily Allah recorded the good and the evil and then made it clear that he who intended good but did not do it, Allah recorded one complete good in his favour, but if he intended it and also did it, the Glorious and Great Allah recorded ten to seven hundred virtues and even more to his credit. But if he intended evil, but did not commit it, Allah wrote down full one good in his favour. If he intended that and also committed it, Allah made an entry of one evil against him.” (Sahih Muslim)
If we make up our mind to do good, Allah would give us a reward for this, since this intention is also an act of piety. It is the intention and the determination which exhort people to do a certain act. Without good intention, there can be no idea of good deeds. If a man puts his intention into practice, he, in fact, makes an advance in virtue, because it demands a good deal of sacrifice on the part of man. This is why Allah in His Infinite Mercy would multiply man’s good deeds.
On the other hand, when he intends to commit evil, but refrains from doing so for the fear of the Lord, he is rewarded by Allah with a good deed, for he has struggled hard to prevail upon his evil self.