The Repentance - 9:5
When the holy months are over, kill the pagans wherever you find them (if they still refuse to make peace). Seize them, encircle them and watch their every move. If they repent and pray and pay zakat, then let them go free. Allah is Forgiving, Merciful.
The importance of zakat:
The Cattle/6:16
Whoever is turned away from torment on that Day, (God) has mercy on him. That is the greatest victory.
The Heights/7:156
"Write for us good in this world and in the Hereafter. We turn to you."He said: "My punishment will touch whom I will. But My Mercy is all-encompassing; I will write it especially for those who lead a righteous life, pay the zakat and believe in Our verses."
The Romans/30:39
The usury money which you give to increase in the wealth of the people does not increase with Allah. But as for the zakat which you give seeking Allah´s Pleasure, those who give it multiply their investment.
The Hypocrites/63:10
"Give out of what We have provided for charity before death comes to you and you say, "My Lord, if only You would postpone me for a short time so that I may be of the righteous by helping the poor"."