Islam teaches that actions are only by intentions and everyone has only that which he intended: ‘Whoever’s emigration is for some worldly gain which he can acquire or a woman he will marry then his emigration is for that which he emigrated.’ Therefore sincerity to God is the key to faith in Islam. Believers are asked to ensure that all acts of worship are done exclusively for God’s pleasure. When actions are only by intentions, it means that deeds are only acceptable and rewarded if the intent behind them is sincere, although sincerity does not change the nature of forbidden actions.
Where a person’s intention is to show off, their acts of worship may be nullified. The greatest action, such as feeding multitudes of the poor, could be reduced to nothing because one’s intention was to earn a good reputation. Yet, at the same time, even the smallest action can be made great by the intention behind it. Good intentions are not spoken for they are matters of the heart of which God is well aware.