Musnad Ahmad 1233:4

Yazid narrated to us, he said: Abu Malik narrated to us, he said: My father narrated to me that he heard the Messenger of Allah, peace and blessings of Allah be upon him, when a man came to him asking him, saying: "O Prophet of Allah, how should I say when I ask my Lord?" He said: "Say: 'O Allah, forgive me, and have mercy on me, and guide me, and provide for me.'" And he closed his palm, except for the thumb, and said: "These gather for you the good of your worldly life and your Hereafter."