وَمَا أَنفَقْتُم مِّن نَّفَقَةٍ أَوْ نَذَرْتُم مِّن نَّذْرٍ فَإِنَّ اللَّهَ يَعْلَمُهُ ۗ وَمَا لِلظَّالِمِينَ مِنْ أَنصَارٍ (270)
(2:270) Surely Allah knows whatever you may have spent and whatever vow you may have made, and the wrong-doers (who spend in the way of Satan) shall have no helpers. *310
*310). Whether or not a man spends in the way of God, and whether or not he vows to spend in the way of God, God is fully aware both of his intentions and deeds. All those who either spend for the sake of God or vow to spend for the sake of God will be adequately rewarded. As for those who have either spent or have vowed to spend for others than God, no one will save them from God's chastisement.
'Vow' means either a man's pledge to spend something or to perform some act of goodness which is not obligatory on him providing a particular wish of his is fulfilled. Provided that this vow is related to some wish which is in itself permissible and good and that the person concerned makes it to none but God and for the sake of God, then such a vow will be reckoned as an act of obedience to God and its fulfilment will be worthy of reward. Otherwise such a vow will be seen as an act of disobedience and sin and its fulfilment will invite punishment from God.