Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.111B.
Section : Raising One’s hands to one’s shoulders..
Ibn ‘Abbas is reported as saying, “When asking for something from Allah, you should raise your hands opposite to your shoulders; when asking for forgiveness you should point with one finger; and when making an earnest supplication you should spread out both your hands.” This is reported by Abu Daw’ud.
Malik b. Yassar reported that the Prophet, peace be upon him, said, “Supplicate Allah with the palms of your hands, and do not supplicate Him with their backs upwards.”
Salman reported that the Prophet, peace be upon him, said, “Your Lord, the Blessed and the Exalted One, is Modest and Generous, and He loathes to turn away His servant empty-handed when he raises his hands to Him in supplication.”