The Reward for Shalom:

The Medrash states (Derech Eretz Zuta, Perek Hashalom, Ois 22): “Rav Yehoshua ben Levi said that Hashem said to Klal Yisroel: You caused My house to be destroyed and for My children to be exiled. You asked about their welfare (shalom) and I forgave you. Why? Because you 'requested the welfare (shalom) of Yerushalaim (Tehillim 122:5).' And it says (Yirmiyahu 29:7): ‘And you requested the welfare (shalom) of the city." And it also says (Tehillim ibid): 'There shall be peace in your walls.' And it also says (ibid): 'For the sake of my brothers and friends.'

"And one who loves peace and pursues peace and who initiates peace and answers with peace, Hashem grants him life in this world and in Olam Haba."