Musnad Ahmad 1018:53

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Abu Mas'ud, from Humayd ibn al-Qa'qa', From a man who began to watch the Prophet of Allah, may Allah bless him and grant him peace, and he would say in his supplication: "O Allah, forgive my sin for me, and expand for me in my dwelling, and bless for me in what You have provided me." Then he watched him a second time, and he was saying the like of that.