He writes that shalom is especially auspicious for parnasah because it is known that peace is a segulah for livelihood, as is stated (Tehillim 147:14): "Within your borders He makes peace; with the best of the wheat, He will sate you." This indicates that peace creates an abundance of crops and parnassah. Furthermore, the Shlah Hakadosh writes (Maseches Yoma, Derech Chaim, Ois 44) that one machlokes pushes away 100 measures of parnassah. On the other hand, every bit of shalom increases parnassah immensely.
This is clearly seen from the Mishnah (Peah 1:1) that states: "These are things that one eats their fruit in this world but the main reward remains for the world to come... and creating peace between a man and his friend." The Rambam writes in his Pirush Hamishnayos that for all mitzvos between man and his fellow man, one receives "fruit" in this world, leaving the main reward for the next. He specifically mentions spreading peace as one of the mitzvos between man and his fellow man that one is rewarded for in this world.
