*1st hadith*:
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In Sunan Abu Dawd. Under Chapter: Washing the hands before eating(12):

>Narrated Salman al-Farsi:
I read in the Torah that the blessing of food consists in ablution before it. So I mentioned it to the Prophet (ﷺ). He said: The blessing of food consists in ablution before it and ablution after it.
Sufyan disapproved of performing ablution before taking food.

[Sunan Abu Dawud - sunnah.com][1]

**Abu Dawud and Albani said: Hadith is weak.**


*2nd Hadith*:
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>Kathir bin Sulaim narrated that he heard Anas bin Malik say:
"The Messenger of Allah (ﷺ) said: ‘Whoever would like Allah to increase the goodness of his house, should perform ablution (wash hands) when his breakfast is brought to him and when it is taken away.’"

[Sunan Ibn Majjah - sunnah.com][2]. **Also Weak hadith**

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Although these hadiths are weak, it is ok to follow them since they are considered  Fada'el al A'amal(فضائل الأعمال). http://islam.stackexchange.com/questions/13272/what-does-fazail-e-amaal-mean/13273#13273

Also, there were no mention of soap. So you are free to use whichever material that helps clean your hands.

  [1]: http://sunnah.com/abudawud/28/26
  [2]: http://sunnah.com/urn/1333850