Is it permissible to raise the hands in supplication during the two prostrations and before the Tasleem, and during some of the opening supplications in prayer, and is it permissible to supplicate with the back of the hand?

Supplication (Du'a) is prescribed in several positions during prayer, such as prostration (sujud), sitting between the two prostrations, and after the tashahhud. The worshiper does not raise his hands in any of these positions, as this was not reported from the Prophet, peace and blessings be upon him. As for supplicating with the back of the hand, this is done when warding off affliction, such as drought. And if one supplicates asking for something, he places the palms of his hands towards the sky.