Musannaf Ibn Abi Shayba 23:79

Abu Mu’awiyah, from ‘Asim, from Abu ‘Uthman, from Salman, who said: It is said to him: "Ask, and you shall be given"—meaning the Prophet, peace and blessings of Allah be upon him—"and intercede, and your intercession shall be accepted, and supplicate, and you shall be answered." So he will raise his head and say: "My Ummah, my Ummah," two or three times. Salman said: "For everyone who has in his heart the weight of a grain of wheat of faith, or the weight of a barleycorn of faith, or the weight of a mustard seed of faith." Salman said: "That is the Praiseworthy Station (al-Maqam al-Mahmud)."