Musnad Ahmad 33:700

Ali ibn Ayyash narrated to us, Shu'ayb ibn Abi Hamzah narrated to us, from Muhammad ibn al-Munkadir, from Jabir ibn Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever says when he hears the call (Adhan): 'O Allah, Lord of this perfect call and the established prayer, grant Muhammad the Wasilah (a station in Paradise) and the virtue, and raise him to the praised station which You have promised him,' the intercession will be made lawful for him on the Day of Resurrection."