In the mosque, some people before raising their hands for making Du'a, rub both their hands against each other, is this Sunnah?
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is a Sunnah to raise the hands when supplicating. The Prophet said: "Your Lord is Hayyiy (which implies bashfulness) and Kareem (which implies generosity), and is bashful to turn away empty the hands of His Servant when he raises them to Him." [Abu Daawood]. However, without any evidence about rubbing both hands against each other before or after the supplication, this matter cannot be legislated as part of the religion. If this is done occasionally without having the intention of it being an act of worship through which one seeks getting near to Allaah there is no harm in it, Inshaa' Allaah, provided that it does not become a habit.
Allaah knows best.
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