It is narrated from Hazrat Salman Farsi (may Allah be pleased with him) that I had read in the Torah that the blessing of food is in washing the hands before it. I mentioned this to the Noble Prophet (peace and blessings be upon him) and referred to what I had read in the Torah. The Noble Prophet (peace and blessings be upon him) said: The blessing of food is in washing the hands before it and also in washing the hands after it.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 23732
Hadith Gradingحکم دارالسلام:إسناده ضعيف من أجل قيس بن الربيع